Knife Steels-Material Science

[Bill Harsey]

I wanted to start a thread about knife steels, kind of a materials engineering topic that would talk about steels used to make knives. This will range from car springs to particle metal steels. We can see if I've learned anything teachable in the last twenty five years of working this stuff.

My hope is to dispel some myths and aid in the maintenance of whatever knife you have or might have to make useful.

The biggest difference between knives is any knife over no knife at all. I'm not going to judge or promote, just trying to help clear up some common misconceptions, if there are any.

More to follow and starting questions welcomed.


In a recent conversation with a QP I learned that field welding can be important. When we get to carbon contents in various steels, I have some useful stuff there too.

There will be as much Redneck Engineering as possible here.

[The Reaper]

Finally, something I know a little about.

If we have not beaten it to death elsewhere, for a starter, I would like to see a little about the older carbon steels, tool steels, stainless and near stainless steels, heat treating, hardening, blade profiles, thicknesses, grinds, bevels, etc.

Just a few thoughts.

TR

[Maytime]

Mr. Harsey,
When you temper your blades, do you use oil or nitrate salt baths?

[Bill Harsey]

Mr. Harsey,
When you temper your blades, do you use oil or nitrate salt baths?
Easy question first, All the steels I use here are air hardening and no oil or salt baths are used or needed.

Reapers question might take volumes but I will use redneck engineering to narrow down the answers.

[The Reaper]

That was not a single question, but was a variety of topics that I would like to know more about.

Hope that at least some of it is in the direction you were looking.

TR

[Bill Harsey]

That was not a single question, but was a variety of topics that I would like to know more about.

Hope that at least some of it is in the direction you were looking.

TR
Yes, you asked a very good series of questions and my response referring to that as a single question was an attempt at understatement.
Yes this is the direction I hoped to go. Well done.

First basic, steel in it's most basic form is iron with carbon. The higher the carbon content, the more the steel can be hardened by heat treating which involves heating a given steel to it's "transformation point" and a rapid, controlled cooling to lock the carbides into a particular type of structure. The more carbon a steel has, the more potential it has to be hardened.
An even simpler definition of heat treating steel is "changing the physical characteristics without changing the chemical composition".

The three most basic categories of steel are Mild Steel, Medium Carbon Steel and high carbon steel. There are many alloys of steels within each of these groups.
Here are some simple examples of the carbon steels:
Low carbon steels: structural steels, car bodies, common steel purchased for welding AKA "mild steel", etc.
Medium carbon steels: Firearm barrels, hammers, gears, axles, spring steels, etc.
High carbon steels: Knives, machine tooling, punches, forming dies, drill bits, milling cutters, saws, spring steels etc.

more to follow.

[Maytime]

note: I find metals fascinating, and as a mechanical engineer I need to know all about their charactersitics, hence the questions, but I have little working experience with high carbon steels like Mr. Harsey uses every day. So...

What is the typical AISI number of steel you use Mr. Harsey?

[Bill Harsey]

note: I find metals fascinating, and as a mechanical engineer I need to know all about their charactersitics, hence the questions, but I have little working experience with high carbon steels like Mr. Harsey uses every day. So...

What is the typical AISI number of steel you use Mr. Harsey?
Maytime,
I have just reviewed my material data sheets for the steels I use here and cannot find any AISI designation and to the best of memory, I've never seen one for either the 154CM I've used so much of in the past or the CPM S-30V we use now.
Both steels are made by Crucible Materials Corporation in Syracuse New York.

Edited to add: Maytime, so you can jump ahead: www.crucibleservice.com

[Bill Harsey]

Finally, something I know a little about.

If we have not beaten it to death elsewhere, for a starter, I would like to see a little about the older carbon steels, tool steels, stainless and near stainless steels, heat treating, hardening, blade profiles, thicknesses, grinds, bevels, etc.

Just a few thoughts.

TR
The topic of alloys is very interesting. Historically some steels were much better than others because the naturally occurring ore dug from the ground contained alloys unknown to the steel makers but beneficial to the performance of the finished blade.
The Indian Wootz steel (think fine Persian blades) of old is a good example of this. When the ancient mine, the original source, of this iron ore played out, the quality of the swords and daggers diminished but no one knew why.

The first alloy of Iron to make steel is carbon. Both high carbon steels and tool steels may contain similar amounts of carbon but not used for the same jobs.
The difference is in the degree of refinement during steel making.

Many truck springs contain .90 carbon content but would not be acceptable for some tool and die jobs needing a tool steel with the same carbon content. This is because the truck springs contain some impurities and inclusions like slag that still make great springs but do not have the grain refinement and purity of manufacturing to hold an extremely fine edge in a hard use production tool.

[The Reaper]

Many truck springs contain .90 carbon content but would not be acceptable for some tool and die jobs needing a tool steel with the same carbon content. This is because the truck springs contain some impurities and inclusions like slag that still make great springs but do not have the grain refinement and purity of manufacturing to hold an extermely fine edge in a hard use production tool.

I have seen some decent knives made from truck leaf springs.

Is this an alloy which has adequate potential to be a good (economical) knife steel, if hardened and heat treated properly?

TR

[Bill Harsey]

I have seen some decent knives made from truck leaf springs.

Is this an alloy which has adequate potential to be a good (economical) knife steel, if hardened and heat treated properly?

TR
Good question and the answer is YES, spring steels, like 1095 can make good knives. They are very forgable and with just a little care can be field hardened and tempered using only the simplest of tools and fire.

I've seen video of full sized jeep springs made into big blades by heating the entire spring, hanger ends and all, over an open fire to orange heat and hammered over a set chisel make the rough cuts then forged to a finished blade. All this with a fire, hammer and crude anvil.

Be careful where you park your jeeps.

If your trying this yourself and in doubt of exactly what steel you have, make a test piece from the steel, heat it up so a magnet no longer sticks to the surface (good indicator of transformation point in simple hardenable steels) and try quenching in warm (100-120 F) 20 weight oil rather than water to minimize the chance of cracking. If it gets hard enough to become difficult to file then the oil quench works. If not try water quench next. If neither of these work, do not proceed with this steel.
Always temper simple tool steels for at least an hour or two at 300-400 F after hardening.

A knife blade can be forged to usable net shape without grinding and made excellent by some simple draw filing.
Yes I've done this before with good results. No real shop needed only some simple tools.

I just received a hard use brush and wood cutting knife from Taiwan, made by an indigenous traditional knifemaker there from leaf spring steel. The knife is very well made and a nice example of direct craft with the file marks part of the design.

[HOLLiS]

My dad had a book, Knights Modern Seamanship. It was written in the 30's. It was a great resource book. It had directions on making a shief knife using a worn file.

Bill do you think old files would be a good source for a knife blank?

[Bill Harsey]

Hollis, A file will make a knife but it's a tough way to go.
Most files are designed to cut steel and have a very high carbon content for maximum hardness. This makes them hard to work (make into a knife) and they tend to be brittle in hard use.

I'd rather go with the spring.

Edited to add: Hollis, by a good source of knife steel, around here that means a steel I can work with in a timely and resource effective manner. Sometimes "free' can cost you a lot of time and money.

A better answer is yes they will make a good knife for some applications but the difficulty of working the file into a usable knife blade would put it down on my list of materials to use.

[Ambush Master]

And then there is passivation in the Stainless Steels!!!:D

[HOLLiS]

Bill, thank you for the reply.

H.

[Bill Harsey]

And then there is passivation in the Stainless Steels!!!:D
I was gonna get here later but since you brought it up...

The trait exhibited by stainless steels not rusting is known as "passivity" and this refers to the material corroding to a point that a film is formed which acts as a barrier to further corrosion.

"Passivation" refers to a process where the stainless steel is, for example, placed in hot nitric acid to remove all surface contamination so nothing is left over from the manufacturing process that will act like a battery on the surface of the steel to set up corrosion. This is not a good process to do on the kitchen stove top.

The term stainless steel covers many types of alloys, the ones we are interested in are the hardenable or austenitizing steels.


Yes there are true tool steels that have good stainless abilities and these are also referred to as "stainless" even though they have little in common with non-hardening stainless steels.

Edited to add a footnote on stainless steels:
High temperature tempering of stainless tool steels can result in a loss of corrosion resistance because chromium carbides continue to form robbing the matrix of usable chromium. See next post.

[Bill Harsey]

We all use tools made of one type of tool steel or another.

Entire libraries are dedicated to this topic and I'm not going to try and fill one up.

The tool steels we use are iron plus alloys carefully chosen by steel makers for certain performance characteristics combined with the ability to manufacture and cost considerations.

The metallurgists I work with call this "tool steel alloy design". They break this down into two basic parts, the matrix and the carbides.

Think of the matrix as the mortar and the carbides as the cobble stones.
Some alloys become the matrix, others produce carbides and some do either depending on the amount used or the type of heat treat.

This is the stuff that determines the traits we choose knives for, like edge holding (abrasion resistance), toughness (strength and ductility)and stain resistance

[Bill Harsey]

How a tool steel is made and heat treated determines the size of the individual carbides.

Anyone care to guess how this impacts knife blades for good or bad?


Not a test, just a conversation.

[gunnerjohn]

OH..OH.. I know!!!
Sorry, I took the class, so I will wait for other answers:D
JJ

[Bill Harsey]

John, Thanks for holding on.
Let's do this different to make it easier, maybe.

Please start naming the knife steels you've heard of or used.
Everyone is welcome to jump in.

[HOLLiS]

Ok, I 'll jump.. My thoughts would be finer is better. Logic would be a more homogenous steel. But I am pretty much guessing. Isn't the difference being disccussed here, pretty small?

[The Reaper]

To name just a few I have seen, A2, O1, O2, D2, L6, W2, M2, 420, 440A, 440B, 440C, 154CM, ATS-34, 1045-1095, 5160, S-30V, and Damascus. Not steels, but also used for blades, Stellite, Talonite, Titanium.

TR

[Bill Harsey]

Ok, I 'll jump.. My thoughts would be finer is better. Logic would be a more homogenous steel. But I am pretty much guessing. Isn't the difference being disccussed here, pretty small?
Hollis,
Yes usually finer grain is better and your logic is correct but not always easy to do in tool steels.

I think the differences between tool steels are surprisingly large and are quite noticable to the user in terms of overall performance and sharpenability.

The performance thing gets important when the knife becomes a life critical tool in an emergency.

[HOLLiS]

I have a book some where that is on heat treating metal. I have a decent size furnace, Nicked named "hades". I think I understand what you are saying. The difference of a small %, or how quickly the quench is, or heated too has a tremedous effect from brittle to too soft (as in not holding a edge).

[gunnerjohn]

Ok.. here is a list of familiar knife steels. The asterik next to some refer to those that are multi task steels, both carbon, alloy and stainless that are used if other applications than just knife steel.

O1*, O2*, A2*, D2*, S7*, W1*, W2*, 440series stainless' A,B,C *, AUS-8, CPM-S30V, CPM S90V, 154CM, ATS34, BG42, 4140*, 4142*, 4145*, 1095*, 1018*, 300 series stainless (303,304,305,316 are used in knife parts, but not blades because they do not heat treat but will work harden when you least expect it. Just ask Bill) A36 is a good carbon mild steel for making other parts, High Speed Steel used in tooling is sometimes used by some makers for it's hardness. Sandvik series 12C27 is an example of a designer steel that is easy to machine in the annealed state, but is tough as hell when hardened which explains the manufacture of machining tools using this material.
Those that like a challange there is also Inconel. This is one of those steels that will belittle the best machine.

[Bill Harsey]

Good list of various steels, I'll begin to categorize soon.


Gunnerjohn,
This is complicated enough without mentioning other materials not used for knives. My poor little knifemaking brain is going to get a stress fracture if you keep this up.

The Inconel type metals (high nickel, chromium, molybdenum and sometimes niobium alloy with very little iron) have no knife blade application that I've ever heard of.

These alloys are designed for being resistant to specific types of corrosion, like in nuclear power generating plants.

Back to knife steels.

[Razor]

Mr. H, how about laminates? Say, as are used in traditional puukkos, with the outer layers soft to allow for a more flexible blade, but the inner layer (the one with the edge profiled on it) being harder to maintain its edge? How does one manufacture them without running into delamination challenges during use?

[Bill Harsey]

Mr. H, how about laminates? Say, as are used in traditional puukkos, with the outer layers soft to allow for a more flexible blade, but the inner layer (the one with the edge profiled on it) being harder to maintain its edge? How does one manufacture them without running into delamination challenges during use?
Good question.

Laminated steels are among the oldest known existing artifacts of iron work ever found in the greater region we now call Syria. (IIRC, from Scientific American article, unkown date) . The oldest known smelted iron ore is said to come from the Sinai Peninsula found in and among ancient copper smelting sites and preceding all this is the near pre-historic use of found meteoric iron by ancient peoples to fashion into tools. This meteoric iron is distinguished by it's nickel content.

High carbon steel was very precious when hand smelting Iron because it either had to be very carefully sorted from the original cooled melt or forged in in a reducing fire of charcoal (source of carbon) to gain enough carbon from "carbon migration" while the steel was at heat. This was some very resource and labor intense work.

I also think that the technologies of making ceramic wares was the source of the technology to smelt the coppers, bronzes and then steels.

To use this hardenable carbon steel frugally, it was laminated or forge welded to another lower carbon steel body to make the entire tool.

The actual "weld" involves heating up both pieces of steel together to just under melting temperature and quickly hammering them together before they cool to the point of not sticking. Fluxes of glassy material are used to float the oxidized steel scale off the surfaces and get a good weld. Steel reacts very quickly with oxygen at high temps and this will prevent a clean strong weld.

When done well, the two types of steel become one piece and can take some very hard use without cracking because the softer outside iron supports the hardened high carbon core that makes up the edge.

The same principles apply to Japanese sword making as well as many carpenters and timber frame tools like old chisels and slicks that can still be found in second hand stores and occasionally estate sales.
Look for the two different colors of steel in the tool body.

If memory serves, we can still buy new laminated wood working tools from some sources, especially fine Japanese woodworking tools.

The traditional Puukkos are a good example of this being done well on a production basis. I think the Puukkos steel is roll forged together in the mill then manufactured into knives. They are famous for toughness.

We also have some custom makers of modern laminated steels that are doing amazing work. My friend www.devinthomas.com comes to mind, he makes some exotic stuff in the high order stainless tool steels.

[Bill Harsey]

Some overview before we go into details later.
You kids see there are a lot of different types of tool steels used for knives.

Many of these tool steels were developed for some other hardened tool steel application than knives, some steels are further developed specifically for blade steels and not just for hand held knives but also stuff like wood chippers, wood milling, steel, plastic, paper and other material cutting blades and industrial scale food machinery as well as the entire range of tooling like drill bits and milling cutters and saws used to machine steel.

The reason we see so many different types of tools steels is that alloys are chosen for particular traits in specific applications or modified as some alloys become scarce or difficult to acquire because of world politics.

The first thing a knife blade has to do is be hard enough so the cutting edge doesn't roll over or break off when we try and cut something. Tool steels need enough carbon to form carbides when hardened.

Other alloys form different kinds of carbides and add to the strength of the matrix but the first and most important alloy of "high carbon" tool steel is carbon in carefully controlled amounts varying from .75% to well over 1% and in the class called "ultra high carbon" a steels carbon amounts can be from 1.25% to 2%.

(darn phone, have business call from Italy, be back later)

Edited to add, It's later:
The main areas of performance knifemakers and users are concerned with are:

Hardness
Toughness
abrasion resistance
stain resistance

These are all mechanical traits of a given tool steel that are both related to each other and quite seperate.

Anyone know the difference between hardness and toughness?

[Maytime]

IIRC, hardness is the resistance to penetration of the surface of a material by a hard object. Toughness I believe is ductile or yield strength. Could be wrong.

[Bill Harsey]

IIRC, hardness is the resistance to penetration of the surface of a material by a hard object. Toughness I believe is ductile or yield strength. Could be wrong.
Correctomundo Sir Maytime.


Hey, I didn't know you guys had computers up in Alaska!

[Bill Harsey]

OK, back to work.
The significance of the hardness and toughness thing goes to not just what alloys are in a tool steel but how the steel is made because this is how carbide grain size is controlled. Carbide size has much to do with toughness, edgeholding and toughness. You will see this material again.

Here is something very important to know about knife steels. The hardness, usually stated in a Rockwell "C" Scale number, is not a direct indicator of blade quality or edge holding. In other words, the higher the indicated Rockwell hardness does NOT mean the knife holds a better edge

[The Reaper]

The first step would seem to be selecting an alloy that has the correct elements with the properties to produce the characteristics we are looking for. Beyond the iron and carbon that define steel, we could add varying quantities of chromium, nickel, cobalt, tungsten, vanadium, molybdenum, niobium, titanium, zirconium, manganese, silicon, or even copper. Each of these, in varying quantities, can give steel specific characteristics. The best known is the addition of chromium to make "stainless steel". Too much or too little, and you get something else.

Once we have the properties we are looking for in the chemical composition, the next step would be to properly harden it to develop the crystalline structure or grain that we are looking for in the various portions of the blade. Steel, even the same alloy, can be heated and cooled to produce everything from a useless paperweight to a superb cutting instrument.

I would think that the grain would be affected by the austenitizing or martensitizing. As noted, steel changes structure and therefore properties during heating and cooling. Some characteristics would be more desirable than others, but you might find both helpful in different areas of the knife. Look at a single-bit axe head with both a cutting edge and a hammering edge on opposite ends, each needs specific properties, yet both are part of the same piece of steel alloy. On a knife, you might want a tougher spine, and a harder edge.

Steel exists in a variety of crystallive forms, Austenite, Bainite, Martensite, Cementite, Ferrite, and Pearlite. Isn't the goal to try and produce more Bainite and Pearlite in the back of the blade and Martensite along the cutting edge? That would seem to be the solution to the toughness vs. hardness quandary. You could ruin a well-selected steel alloy for your knife by improperly heat treating it, or optimize a lesser steel for your purpose with a good heat treat.

Obviously, the knife cuts on its edge. You can use a knife for a pry bar, but it is not optimized for that. The edge of a well honed knife is not smooth, as most people think, but is very jagged. That is how it cuts. When the carbides and crystals at the edge are very hard, but the steel matrix is not, you get an optimized edge for cutting, yet is easily sharpened. The Crucible S30-V has the right carbides to work for this process. It is up to the knifemaker to expose them at the edge, and bring the hardness and toughness to the different parts of the blade, as required.

IIRC, the Japanese bladesmiths produced some very fine blades with little knowledge of metallurgy or chemistry by proper heat treating. They kept the spine softer and tougher, while creating the harder, better curtting Martensite along the edge by an advanced heat treat. As I understand it, the blades were generally straight prior to heat treating, and the curve of the Japanese sword occurred due to the properties and structure of the steel changing along the different parts of the blade durting their heat treat.

Just a few thoughts, probably in over my head, but I got that way by listening to smart people. Back to my cave.

TR

[swatsurgeon]

This question will likely show my ignorance but.....are there any blade makers doing the old Japanese techniques that we've heard about that give 'legendary' strength and edge to a blade...or is it all myth.

ss

[Bill Harsey]

Reaper,
Highly simplified response to your comments and question.
Each type of tool steel has a range of hardnesses it can be hardened and tempered to and as you indicate with the example of the Axe, you can have two (or more) different hardnesses in the same finished tool.

Differential hardening is easier to do with water and oil quenching hardenable tool steels but does happen to some smaller degree with the air hardening tools steels which tend to be much more homogeneous in the heat treat because the quench time isn't quite so critical.

While on the topic of hardnesses, they are many wrong ways to get the "correct" Rockwell hardness scale reading that result in a steel not being as good as it could be. Rockwell hardness is a test to be used in the shop under controlled heat treat conditions in order to be understood and used well.

The Japanese sword smiths, who mastered the craft well over 700 years ago, may not have understood the science of what they did but they fully understood the process that produced the best results and did it very well.

Remember, this is when all steel was "hand made" with charcoal fired melts and forges way before big power sources and mills.

Swatsurgeon, Yes we have modern makers of traditional sword making techniques that are doing very good work.

Yoshindo Yoshihara (check this next link out!) http://www.legacyswords.com/Yoshiharanihonto.htm from Japan comes to mind. My friend Bob Lum (knifemaker) met with him last week in New York City at the big knife show there.
Note the well defined differential hardening in the images.
Note the price the set of swords sold for at the end.

[The Reaper]

Bill:

Can you comment on forged blades, versus stock removal, and the effect of the forging on the steel grain and crystalline structure?

TR

[Bill Harsey]

Bill:

Can you comment on forged blades, versus stock removal, and the effect of the forging on the steel grain and crystalline structure?

TR
Good question.
Historically the only way to refine a steel was by hand hammer forging (drawing out), re-stacking the steel and forge welding solid then forging it again, repeat until good results which if you made swords meant making swords that didn't break or bend easily.

This concept for steel refining was done on a much larger scale in the big steel mills into the early 1900's. English Shear Steel was a good example we know about in Oregon because this was how the plate for really big circular saw blades used in the sawmills was made.

Forging breaks up the large crystal/grain structures that resulted during the original melt of steel cooling into an ingot. Alloys tend to gather together during the initial cooling and form large crystals that would be too large and brittle to make into strong steel.
Now we are using steels that are highly refined during the steel making and forging (rolling into usable bar stock or sheet) processes. I seriously doubt any positive change in the steels grain structure can be accomplished by forging many modern tool steels.
Many of the top metallurgists in the country will back me up on this.

With some of the steels we use forging can easily cause more damage than good and the best the bladesmith can hope for is not ruin the steel when they forge the exotic (highly alloyed) steels. This is because the temperature range at which the steel can be forged is both high and narrow. Forging the steel outside these heat ranges can/will cause damage like the grain tearing apart resulting in cracks that will propagate during heat treat or use.

We are lucky to have many accomplished bladesmiths working in the world today and I don't want them hunting me down for any perceived slight to their craft. Keep working guys!
Industry will never duplicate the fine craft of forge welded patterns and making steel into blades like these guys do using the straight high carbon steels and I have the highest respect for the work being done.
This is what Yoshindo Yoshihara and his brother are doing, keeping a fine craft alive. They do amazing work at the forge.

Edited to continue:
Stock removal is the shop practice of knifemakers (myself included) of purchasing a particular type of steel, chosen for a range of best possible performance characteristics, which is roll forged into a specific shape and thickness of either bar or sheet.

Upon arrival in the knife shop the steel is then formed into a knife blade by cutting, abrasive grinding, machining, heat treating and finishing.

These steels have undergone considerable forging processes under tightly controlled temperature and atmosphere conditions in the mills before they arrive in the shop. Optimum heat treat and control of manufacturing process is the key to good results with these steels, not forging in the knife shop.

[Bill Harsey]

Before this rodeo gets out of control with too much detail and I lose all interested readers, I'll try to explain why we are going into this detail.

A knife cuts well because of how the cross section of the blade is shaped or what knifemakers call blade and edge geometry.

The thinner the blade and acutely sharper the angle of the edge, the better it will cut.

The limiting factor on blade geometry is the strength of the steel and even the size of the carbides.

When we have a given blade steel with optimum heat treat and we need it to stand up to increasingly tougher jobs, the only way to make it stand up to the demands is to increase the thickness of the blade and the edge. Think of how swords are different than paring knives.

About carbide size
I've worked with the tool steel called D-2 for many years. It's a common planer blade steel used in my regions sawmills. People keep bringing me handfuls of used planers blades made of this stuff. I keep thinking it might be useful for something someday. The pile keeps growing.

Much of the D-2 I've actually made into knives and master drill/machining patterns was purchased new. Here is the thing with D-2, it has the largest carbide size of any tool steel i know about. This is a problem because you CANNOT place an extremely fine or acute edge on a blade made from this without having carbide chip-out on that edge.
Edges on D-2 have to be less acute of an angle.
The macro grain on this steel can be seen thru the grinding and buffing stages of finishing the blade.

There can be very large and discernible differences in how tool steels perform when made into knives.

Edited to add: D-2 is a legitimate knife blade steel. Some good knifemakers use it very successfully.
Here is the difference, you cannot grind D-2 into a super thin edge (like .015 to .007 thousandths of an inch thick before first sharpening) and expect it to hold up. It has to be left a bit thicker and I'd be comfortable with an edge thickness more like .035 thousandths of an inch thick for a folding knife or fixed blade hunter.
D-2, because of it's big carbide/grain structure does not have the transverse bend fracture strength of other tool steels so the edge will not stand up as well to prying or side load.

[Bill Harsey]

Carbide grain size can be measured and documented with a scanning electron micrscope. I do not have one of these in my shop but the metallurgists whose phone no.s I keep handy do.

One of the finest grain tool steels available (not stainless) is called 52100 and is made by Timken-Latrobe here in the USA. This is a bearing and bearing race steel and be gotten very hard by heat treat. This steel has gained favor among many bladesmiths.

Anyone care to guess how a steel testing softer on the Rockwell hardness scale can out perform the 52100 in edge holding type cutting tests?

[The Reaper]

Edited to add: D-2 is a legitimate knife blade steel. Some good knifemakers use it very successfully.
Here is the difference, you cannot grind D-2 into a super thin edge (like .015 to .007 thousandths of an inch thick before first sharpening) and expect it to hold up. It has to be left a bit thicker and I'd be comfortable with an edge thickness more like .035 thousandths of an inch thick for a folding knife or fixed blade hunter.
D-2, because of it's big carbide/grain structure does not have the transverse bend fracture strength of other tool steels so the edge will not stand up as well to prying or side load.

Does this acount for the joke about D2 taking a crappy edge and holding it forever?

I have also heard it has a rep for not polishing well due to the orange peel surface.

The D2 I have carried is superb.

BTW, I had a scholarship from Latrobe Steel, they were good people.

Timken is famous for their fine bearings. I had no idea they had merged.

TR

[Bill Harsey]

Does this acount for the joke about D2 taking a crappy edge and holding it forever?

I have also heard it has a rep for not polishing well due to the orange peel surface.

The D2 I have carried is superb.

BTW, I had a scholarship from Latrobe Steel, they were good people.

Timken is famous for their fine bearings. I had no idea they had merged.

TR
Reaper,
Here is the problem getting information from some knifemakers. A number of us are using very high performance steels, the state of the art stuff ever produced on this planet (and if some of you guys have access to other stuff, pm me here. :D ) Our, ok MY, opinion is going to be a little biased and I'm trying to keep the bias out of this. That said...this isn't going to be a perfect comparison but here goes:

If we compare knives to NASCAR, I'm used to building cars that do 220 MPH all day long on the track. Your D-2 steel only does 200 because of some limitations on blade geometry and ultimate strength imposed by grain structure. Your D-2 also doesn't have rain tires.


On the street, 200 mph capability is damn hot performance.

The average day to day pocket knife user needs a "steel" that can do 60, top speed and are satisfied with the job it performs because they know it's limitations (don't pry the split rim off the farm truck wheel with it...) and can probably do the basic work of sharpening to keep it cutting.
All knife steels will need sharpening at some point.

The potiential life critical tasks demanded of a knife by those who would be in tactical or emergency situations is the reason good knifemakers use the best steel possible

Amazing knives have and are being built from D-2 but the grain size and carbide saturation present some limitations in some areas of performance.
Yes D-2 is a little hard to polish but there are others that are tougher to fine finish.

If all my knife making got limited to D-2, right now, I'd still make very good knives but no filet knives at Rockwell "C" scale 60 that can bend near 90 degrees are going to be made from it.

I also know the maker of your D-2 knives and he has the process down to a science for best possible results.

Very cool on the scholarship from Latrobe.

[Bill Harsey]

What makes a knife stainless?

Can a tool steel be stainless?

[The Reaper]

What makes a knife stainless?

Can a tool steel be stainless?

10-12% or more Chromium (Cr) content generally defines a "stainless" steel, though Cr content can run as high as 30%. Not sure how knife steel is defined versus normal metallurgical steel definitions.

IMHO, D2, at 11-13% Cr, is technically a high-carbon, high-chromium cold work tool steel. Depending on the exact amount of Cr, it could be stainless, or it might be very nearly stainless.

A little metallurgical poem, from one of my favorites.

"Gold is for the mistress - silver for the maid
Copper for the craftsman cunning in his trade.
"Good!" said the Baron, sitting in his hall
But iron - cold iron is the master of them all."
-Rudyard Kipling

TR

[CPTAUSRET]

If this question has already been covered, please ignore.

What about Cryogenics, is there a serious usage in cutting steel?

Terry

[Bill Harsey]

If this question has already been covered, please ignore.

What about Cryogenics, is there a serious usage in cutting steel?

Terry
Do you refer to the sub-zero quench used in the heat treat process?

I haven't given up on the stainless question yet...Reaper has good answer but there is more.

[CPTAUSRET]

Do you refer to the sub-zero quench used in the heat treat process?

I haven't given up on the stainless question yet...Reaper has good answer but there is more.


Bill:

This process. http://www.nitrofreeze.com/

Terry

[Bill Harsey]

Bill:

This process. http://www.nitrofreeze.com/

Terry
Terry, Much to this.
I always use liquid nitrogen (-320 F) as an integral step during the heat treat of the steels I use here, so does Chris Reeve. This is critical to the ultimate performance of the blade steels we use but is only good if integrated at the correct time during the hardening and tempering process.

There is much discussion about how much good a cryogenic treatment does after the part has concluded it's heat treat and has been made into a finished part.

[CPTAUSRET]

Terry, Much to this.
I always use liquid nitrogen (-320 F) as an integral step during the heat treat of the steels I use here, so does Chris Reeve. This is critical to the ultimate performance of the blade steels we use but is only good if integrated at the correct time during the hardening and tempering process.

There is much discussion about how much good a cryogenic treatment does after the part has concluded it's heat treat and has been made into a finished part.

Interesting!

Good thread, Bill!

Terry

[mumbleypeg]

I'm just venturing a guess on the Stainless/ Tool steel question. Tool steels have higher carbide content which gives them their hardness. (here comes the guessing) Stainless has a higher chromium content which increases corrosion resistance but limits the hardness.

BTW, great thread.

[Maytime]

For the stainless tool steel question: My answer is yes, you can have a stainless tool steel.

Reasoning: It may have to be a precipitation-hardened, nonstandard chromium steel, AISI types 632-635. I chose the precip-hardened steel since the Martensitic grade is heat treatable, while the Austenitic grade allows you to add an array of elements to change formability (Cr-Ni), intergranular corrosion resistance (Mo), hardness (C), etc.

TR probably answered most of it; I don't have the numbers in front of me to compare the aforementioned steels to tool steels.

[Bill Harsey]

CPTAUSRET,
After main work hours, here's more answer to your question about cryogenic treatment of tool steels.

The reason we deep freeze tool steels is to force retained austenite produced during the high temperature phase to convert to martensite.
This happens because the freezing increases the mechanical driving force in the steel to complete this transformation.
This must be done during the initial heat treat cycle or the steel tends to "set" and the freeze will have much less ability to do any good.

Retained austenite in the steel causes weakness and we don't like weakness around professionalsoldiers.com. Just ask the Team Sergeant.

[Bill Harsey]

I'm just venturing a guess on the Stainless/ Tool steel question. Tool steels have higher carbide content which gives them their hardness. (here comes the guessing) Stainless has a higher chromium content which increases corrosion resistance but limits the hardness.

BTW, great thread.
Your more right than you know. There is an entire area on the "tool steel alloy composition chart" where tool steels are stainless because of the addition of chromium. You swerved into something here too, too much chromium displaces other alloys and isn't as hard of a carbide.

Maybe I should explain what knifemakers call stainless, tool steels containing 14% chromium are considered pretty stainless. 14% is the threshold of "stainless" in a tool steel. D-2 has about 12% chromium and has some stainless characteristics but is more prone to the surface discoloration some folks call rust. The D-2 certainly doesn't rust much compared to other non-chrome tool steels.

An interesting thing to know about 14% chromium tool steels like 154CM (common good blade steel) is that the kind of heat treat can change the ability to not stain. Some of these steels have two distinct final temper ranges, high and low. When 154CM is tempered in the high temp range of over 900 F, the chromium carbides continue to form thus pulling usable chromium out of the matrix for stain resistance. The difference is noticable especially with 154CM knives used around salt water.

[Bill Harsey]

For the stainless tool steel question: My answer is yes, you can have a stainless tool steel.

Correct.
The term "stainless steel" got a deservedly bad reputation back when manufacturers figured out that you don't have to use a good grade or do a good heat treat to sell knives. Hard use knife folks got it and the word was "stainless sucks".

Much has changed. For one the business of selling knives is very competitive and if quality slips, someone else gets your market share.
Steel companies are supplying good working grades of these steels on a regular basis to knife companies who are careful to get the heat treat right because reputation is everything.
We now have more metallurgists than ever before working directly with knife companies to keep this stuff sorted out.
(I keep my metal guys on speed dial.:D )

The knife buyer is the winner.

Now we have a grades of stainless tool steels with hardness, toughness and abrasive resistance properties that few tool steels could even dream about 20 years ago.

[The Reaper]

Bill:

Let's cut right to the chase.

If you had to build a fixed blade knife that was going to be your only tool to survive with out in the woods (in combat), and you could have any alloy you wanted, in the dimensions you wanted, what steel would you pick?

What would it be for a folder?

That is really what we want to know.:D

TR

[Bill Harsey]

Bill:

Let's cut right to the chase.

If you had to build a fixed blade knife that was going to be your only tool to survive with out in the woods (in combat), and you could have any alloy you wanted, in the dimensions you wanted, what steel would you pick?

What would it be for a folder?

That is really what we want to know.:D

TR
The same stuff I'm using now, CPM S-30V for both.

Edited to add, some may be familiar with a few of the knives made with this steel.


Edited to continue: Reaper, as you probably know, we never stop testing new steels as we can get our hands on them. Yes there are a couple very exotic and difficult to work steels that can do a thing or two better than CPM S-30V and they are very cost prohibitive to manufacture and there will be huge downsides to the user.

These steels would defy re-sharpening in the field making them of little use to the soldier.


My answer remains CPM S-30V steel.

[Bill Harsey]

As is beginning to be discussed here, tool steels are made from many different recipes of alloys.

The purpose of these choices is to try and combine multiple physical properties we want in a single piece of steel for a specific edged tool.

For a knife we want it to get sharp and stay sharp as long as possible while being able to use as a prybar if needed. These are two distinct and seperate physical properties.

Stain resistance is important to "sharp". We can lose the edge on a non-stainless knife without ever using it if your in the right geographic location like a warm marine or tropical climate.

If we pick any single steel designed for a single trait, there will be many other steels that do the other traits better.

These are some of the things we have to think about when choosing a tool steel for extreme use knives.

We haven't spoken about "particle metal steels" yet (CPM S-30V is one of them)... this stuff is gonna get like science fiction, only better. :lifter

[12B4S]

Correct.
The term "stainless steel" got a deservedly bad reputation back when manufacturers figured out that you don't have to use a good grade or do a good heat treat to sell knives. Hard use knife folks got it and the word was "stainless sucks".

Much has changed. For one the business of selling knives is very competitive and if quality slips, someone else gets your market share.
Steel companies are supplying good working grades of these steels on a regular basis to knife companies who are careful to get the heat treat right because reputation is everything.
We now have more metallurgists than ever before working directly with knife companies to keep this stuff sorted out.
(I keep my metal guys on speed dial.:D )

The knife buyer is the winner.

Now we have a grades of stainless tool steels with hardness, toughness and abrasive resistance properties that few tool steels could even dream about 20 years ago.


Speaking of hardness and toughness. In the mid 70's I got a Puma Skinner. Still have it. Up the blade is the 'diamond punch mark' Did a quick search on the net. The design is like the top knife in that pic. However, There isn't any etching/writing on that side of my knife. It is on the opposite side and different. it is the 6393, serial # 56472.

http://www.foxridgeoutfitters.com/detail.cfm?section=12&subsection=131&product=4109

[Bill Harsey]

Speaking of hardness and toughness. In the mid 70's I got a Puma Skinner. Still have it. Up the blade is the 'diamond punch mark' Did a quick search on the net. The design is like the top knife in that pic. However, There isn't any etching/writing on that side of my knife. It is on the opposite side and different. it is the 6393, serial # 56472.

http://www.foxridgeoutfitters.com/detail.cfm?section=12&subsection=131&product=4109
Brad,
I'll assume your asking what steel this is and I don't know but I can ask the owner of Boker or his top knife designer over in Germany. Everyone knows what their competitor is doing.

The "diamond punch mark" is the impression left by the point on the Rockwell hardness tester. The diamond is gently preloaded onto the flat and parallel surface of the heat treated blade, while it rests on the machines anvil, then a known pre-set load is applied. The depth of this impression is carefully gauged by a large readable dial on the Rockwell hardness tester and the user reads off the hardness.
The less the penetration, the harder the steel.

A Rockwell Hardness test is that of testing a given steel or other materials ability to resist surface indentation.

[The Reaper]

In selecting steel, what we really need to do first is to determine what we want the blade to do.

The use of the item, and the characteristics we need will decide its optimal composition.

A soldier, a butcher, a surgeon and a gift-wrapper may all use knives, but what they are doing with them are completely different, as are their ability to maintain them. A surgeon may toss a multi-hundred dollar instrument, the soldier spend it reluctantly, but be unable to care for it and maintain it like the butcher, where the gift-wrapper will not spend over $10 for one, and will probably throw it out (or change blades) when dull.

The best steel is always going to be a compromise between multiple factors, only the user can decide whether a particular product is worth the price. For the soldier, I believe that the primary characteristic sought is toughness. For the butcher, it may be edge-holding, for the surgeon, it may be sharpness, for the gift-wrapper, it may be price.

Speaking of price, I know that steel prices are a portion of the finished product's costs, and that the time and abrasives it takes to prepare the steel is another portion of the cost. Clearly, CPM S-30V is a great steel for those serious users who can afford it, but is may not be the right steel for a knife going on the shelves at your local Wally-Mart.

Bill (or Mick, or any of the other makers here), can you elaborate at some point on the relative prices of the steel, the abrasives, the heat treat, and the time spent working it to the final cost of the knife?

Thanks much, great thread.

TR

[Bill Harsey]

Reaper,
Good overview, Your spot on about many things in your comments.

It is like trying to hit a moving target to find a tool steel that gives us the desirable performance traits in a knife and it does depend on the job your doing.

Let's stick to tactical knives and please remember:

"The biggest difference between knives is any knife over no knife at all"
(-Bob Loveless 1986, while I was his guest in his shop)

Yes we are guilty of trying to make the best possible knives with the best possible steel and it doesn't come cheap. The better the steel, the higher the price and we pay a premium for the steel alone and because of the properties we desire in the knife this correspondingly makes the manufacturing costs higher because of hardness and toughness to machine, grind and finish correctly .

CPM S-30V is running right at three to four times as expensive as other tool steels that knives could be made from. I haven't gone down the list of alloys and what they do yet so here is a start because it goes to "cost of making"..

CPM S-30V has, among other things, Vanadium in it, enough to form Vanadium carbides. Vanadium carbides are harder than the abrasive grit aluminum oxide. This is why this steel has some very good edge holding and abrasion resistance and it really sucks to grind and finish compared to other tool steels at the same hardness.

World markets are directly effecting the price we pay for steel. There is great competition for iron and all the other alloys that go in it. China is a huge factor in this situation. I'm seeing "surcharges" on my steel bill because of the added cost of getting particular alloys from various parts of the world.
This all goes to cost of manufacturing.

We also think the performance gained, as measured in toughness, edge holding and stain resistance, is worth it in life critical tools.

I would still take the knife forged out of a truck spring over no knife at all.

[12B4S]

[QUOTE=Bill Harsey]Brad,
I'll assume your asking what steel this is and I don't know but I can ask the owner of Boker or his top knife designer over in Germany. Everyone knows what their competitor is doing.

I only knew the purpose of the Rockwell Hardness test, but now I know how it is done. Thanks. It would be interesting to know the type of steel but if it’s a hassle it’s don’t bother Bill. What I was trying to find out, while trying to sharpen it a few months ago, was whether it was a double or single bevel edge. I’ve had it for some three decades and don’t remember. Even looking through a magnifying glass it’s hard to tell. Reason for that is because I have tried sharpening both sides. I began wondering if maybe it was designed and made with a single edge.

[Bill Harsey]

Brad,
If memory serves, the Puma Skinner had a nearly sharpened top edge for bone breaking when working on big game. It was designed to be turned over and used like an axe.
My thought is concentrate on the main master bevel for hunting uses, the top edge doesn't have the geometery to get sharp easily.
I've worked on those knives before.

[12B4S]

That it does Bill. I'm just not using the right nomenclature. I mean the edge. Whether it it sharpend on one side or both sides of the blade.
Brad, Bill here, let me answer within your post. Understand now, sharpen the blade from each side. If a blade has been sharpened unevenly it may be hard for you to see in order to figure that out.
Does this answer your question?

[Bill Harsey]

Hey Class! I almost forgot-
The Crucible Specialty Tool Steel metallurgists and management YEARS AGO named me the official "Caveman Testing Facility". Whenever they come up with something new, they send it to me for testing to see if it can be heat treated here, successfully. If it passes the "caveman test" they can go to market knowing virtually all machine shops can handle the steel well or have little excuse for not doing so.
Here's why I bring this up...
I'd thought I'd try and get "sooophisticated" on ya all and see if some research on alloying elements would be of any benefit to explaining this stuff to you here on this thread.
I quickly found so much empty or half complete information via Google that I came to my senses and we're gonna do it my way.

Next Installment: Tool Steel Alloys and what they do, caveman style :D

[HOLLiS]

Hey Class! I almost forgot-
The Crucible Specialty Tool Steel metallurgists and management YEARS AGO named me the official "Caveman Testing Facility". Whenever they come up with something new, they send it to me for testing to see if it can be heat treated here, successfully. If it passes the "caveman test" they can go to market knowing virtually all machine shops can handle the steel well or have little excuse for not doing so.
Here's why I bring this up...
I'd thought I'd try and get "sooophisticated" on ya all and see if some research on alloying elements would be of any benefit to explaining this stuff to you here on this thread.
I quickly found so much empty or half complete information via Google that I came to my senses and we're gonna do it my way.

Next Installment: Tool Steel Alloys and what they do, caveman style :D

Yeah,,,,,,,,,,,,,, Caveman style, works for me, Let me go get my bigger hammer................

Thanks for the Thread BTW, Very enjoyable read..

[Bill Harsey]

Iron makes up most of "steel" but it is usually never mentioned in the chemical analysis or composition of added elements that make up tool steel alloys.

Tool steels are made and refined by several different processes but they all involve getting it very warm until liquid and then the alloys can be added to the melt.

This is done in amounts measured in tons at a time. I asked the Crucible steel guys if I could come help make steel sometime. They said no.

While a tool steel is molten samples are taken from the batch, cooled and tested for percentages of added elements. Adjustments are made on the fly.

Here are some of the alloys added to tool steels I know about, anyone notice anything a little unusual in the list?

Carbon
Chromium
Cobalt
Columbian(bium...:D, now called Niobium the last century or two)
Molybdenum
Manganese
Nickel
Nitrogen
Phosphorus
Sulfur
Silicon
Tungsten
Vanadium

Some of these strengthen the matrix, some make carbides and some do both.
There are other reasons that alloys are added to steel, like for example, improving the steels ability to cool down from the initial melt without massive segregation of alloys.

[The Reaper]

Here are some of the alloys added to tool steels I know about, anyone notice anything a little unusual in the list?

Carbon
Chromium
Cobalt
Columbian
Molybdenum
Manganese
Nickel
Nitrogen
Phosphorus
Sulfur
Silicon
Tungsten
Vanadium


Bill:

Don't want to ruin your alloying here, but if you put your Columbian in the steel, he (or she) is going to scream and flop about before ruining the steel.

I had no idea human sacrifice was a part of steel making any more.

You Oregon boys have all of the tricks.

TR

[Bill Harsey]

TR,
Our carbon comes from a different source and I don't think I've ever used a steel with Columbian in it.

Look at the list again, aren't alloys supposed to be a solid? :munchin

[Air.177]

TR,
Our carbon comes from a different source and I don't think I've ever used a steel with Columbian in it.

Look at the list again, aren't alloys supposed to be a solid? :munchin


I am completely out of my lane here, but could the Nitrogen come from the Liquid Nitrogen that you referred to earlier in this thread?

[Bill Harsey]

I am completely out of my lane here, but could the Nitrogen come from the Liquid Nitrogen that you referred to earlier in this thread?
Air.177, you have the correct stuff but not at that stage.

In some steels (like the ones we use) Nitrogen is injected into the melt and it reacts at the molecular level with the steel.

Anyone guess what it forms?

[Maytime]

Anyone guess what it forms?

When nitrogen is heated, it combines directly with lithium, magnesium, and calcium, and when mixed with oxygen, it forms nitric acid then nitrogen dioxide. I believe large quantities of nitrogen are used to anneal stainless steel IIRC.

[Bill Harsey]

When nitrogen is heated, it combines directly with lithium, magnesium, and calcium, and when mixed with oxygen, it forms nitric acid then nitrogen dioxide. I believe large quantities of nitrogen are used to anneal stainless steel IIRC.
To the best of my knowledge there is no lithium, magnesium, calcium or oxygen in the melt when making the CPM steel that Nitrogen is used in.

[Ambush Master]

Bill,
Are you talking about the use of a high pressure jet of N2 to produce the fine particles of extremely homogenious material that Crucible uses?!?!

[Bill Harsey]

Bill,
Are you talking about the use of a high pressure jet of N2 to produce the fine particles of extremely homogenious material that Crucible uses?!?!
That is in use too but I'm not sure that's how it gets in the mix.

The result of the nitrogen content are Nitrides which are like carbides.

Laying all my cards on the table face up for this one question, the process by which it's done is at the very least proprietary if not "classified" a little higher.

They won't tell me how it's done.:mad:

[Ambush Master]

That is in use too but I'm not sure that's how it gets in the mix.

The result of the nitrogen content are Nitrides which are like carbides.

Laying all my cards on the table face up for this one question, the process by which it's done is at the very least proprietary if not "classified" a little higher.

They won't tell me how it's done.:mad:

Bill,

I think that they are hiding it right out in the open!!!

Nitriding is a "Case Hardening" process, ie Surface, and if these nitrides are throughout the material, it is getting there during the atomization of the molten material. When the resultant particles are placed into the container, sealed, and then hot isostatically pressed, the N2 that is present in the droplets has no place to go and remains as an integral part of the mix!!!:munchin

Later
Martin

[The Reaper]

Not sure that we really want to get into the details here, even if we knew.

Some jerk in China is probably already trying to figuire out how to knock off a copy of CPM S-30V and make it for half the price.

Just my observation.

TR

[Alchemist]

Mr. Harsey,

Fascinating thread! I don't know much about materials science, but there's enough chemistry here for the topic to feel just a little familiar, and I've enjoyed learning more.

Here are some of the alloys added to tool steels I know about, anyone notice anything a little unusual in the list?

Speaking just as a fool chemist, I wasn't surprised by nitrogen, because I'd read that metal nitrides can be extraordinarily hard. If I were more timely I'd have offered phosphorus. (Since it's considerably larger than nitrogen, if you could take a metal nitride structure and substitute P for N, you'd disrupt the crystal lattice quite a bit.) From a quick Google search, most hits had to do with removing phosphorus that was present as an impurity, to avoid excessive brittleness. Are there instances where you'd want to add it on purpose? Or is it an element that tends to be present anyway, and you have to go to some effort to remove it? Sorry if this naive or off-topic.

[Bill Harsey]

Mr. Harsey,

Fascinating thread! I don't know much about materials science, but there's enough chemistry here for the topic to feel just a little familiar, and I've enjoyed learning more.



Speaking just as a fool chemist, I wasn't surprised by nitrogen, because I'd read that metal nitrides can be extraordinarily hard. If I were more timely I'd have offered phosphorus. (Since it's considerably larger than nitrogen, if you could take a metal nitride structure and substitute P for N, you'd disrupt the crystal lattice quite a bit.) From a quick Google search, most hits had to do with removing phosphorus that was present as an impurity, to avoid excessive brittleness. Are there instances where you'd want to add it on purpose? Or is it an element that tends to be present anyway, and you have to go to some effort to remove it? Sorry if this naive or off-topic.
Alchemist, It's an honor to have you here, thank you for reading.
I have someone hanging out in the shadows that may be more able than I to answer your question but yes I do use steels that try to minimize the phosphorus.

You have some (deep) background in organometallic chemistry, that sounds close enough to knifemaking for me, Sir. :D

[Bill Harsey]

Here's a red-neck engineering attempt at tying up some of the loose ends about how tool steels harden.

We've already used the term Austenite or Austenitizing here without much of an explanation. If we get some understanding of this word, it will help us know what happens when heat treating tool steels for use as edged tools.

Austenite is the word used to describe the solid solution of Iron and carbon, when steel is heated above it's critical temperature (something like 1450 Degrees F for simple water or oil hardening tool steels, much higher like 1950-2150 F for air hardening steels).

When the steel is cooled quick enough this turns the carbon and other alloys which can form carbides into hard Carbides and that's called "Martensitic Transformation". All during this the steel remains the exact same chemical composition but it's a different shaped atomic structure because of where the carbon and Iron atoms freeze into place depending upon rate of cooling. Cementite (Iron Carbide) is produced in here somewhere too.


If the steel is cooled slowly, this hard carbide formation doesn't happen.

We control the rate of cooling from the austenitizing temperature to get a particular range of physical characteristics, like hardness, toughness and edge holding in the tool steel being made into knives.

Usually this "rate of cooling" is exactly as fast as we can get away with while not cracking the work piece. The thicker the work or more complex the shape, the more careful we have to be about cooling too fast.

The alloys and percentages of these alloys will determine the physical characteristics of the steel and how it is heat treated, that is quenched in water, oil or air OR a combination of oil/air interrupted quench etc.

[Bill Harsey]

For The Reaper and other scientifically distinguished company around here like Mr. Dick Barber and Alchemist:
Yes I left out the other good stuff in steels like pearlite, bainite and other phase changes in the steel structure and time/heat graph because quite simply, I can't explain them.

There's a whole lot of rockin' and rollin' going on at the atomic level when we heat treat this stuff.

[Ambush Master]

Cool............Very Cool...........What about Cryogenic Tempering?!?!:D

Later
Martin

[The Reaper]

For The Reaper and other scientifically distinguished company around here like Mr. Dick Barber and Alchemist:
Yes I left out the other good stuff in steels like pearlite, bainite and other phase changes the in the carbon and iron time/heat graph because quite simply, I can't explain them.

There's a whole lot of rockin' and rollin' going on at the atomic level when we heat treat this stuff.

Sir, I am afraid that you have me confused with someone else. I am just an old, broken-down, former action guy.

TR

[Bill Harsey]

Cool............Very Cool...........What about Cryogenic Tempering?!?!:D

Later
Martin
Freeze treatment (from -100F to -320F) after the initial hardening steps described above continues the transformation of the carbides for better and stronger steel. Said another way:

The deep freeze increases the driving force inside the steel to force the completion of the austenite to martensite transformation.

It is critical that this step is followed by a heat tempering cycle, well under the transformation point, to remove just a bit of hardness from the steel to keep it from being too brittle for use.

I use liquid nitrogen for the cryo step here, that's -320 F.
Personally I won't let steel set overnight from the deep freeze cycle but always get it right back up to room temp and into the first temper cycle to make sure it doesn't sit there and break itself because of the tremendous stresses being generated inside.

[Bill Harsey]

Sir, I am afraid that you have me confused with someone else. I am just an old, broken-down, former action guy.

TR
Sorry Reaper, not buying this one.

[Bill Harsey]

I don't think we talked about a question asked earlier:

Can a knife steel that isn't as hard as another knife steel have better edge holding?

[The Reaper]

Can a knife steel that isn't as hard as another knife steel have better edge holding?

Yes.

TR

[HOLLiS]

I don't think we talked about a question asked earlier:

Can a knife steel that isn't as hard as another knife steel have better edge holding?

Yes,

[Peregrino]

Yes.

TR

OK - I'm sacrificing myself for the greater good. I don't normally throw myself on live grenades but this one I've got to see. What's confusing me is the definition of hardness. Rockwell #s aside, I thought hardness (as a factor in edge holding ability) was a function of % of carbon in the steel, the heat treat, and the resulting grain size and density of the carbides. Softer steel = fewer carbide crystals in the iron matrix. (Assuming a quality heat treat with controlled grain size/growth that doesn't leave the steel brittle and prone to cracking.) Since the exposed carbides (ideally troosite after martensite is converted during tempering) along the edge (earlier lecture on S30V) do the cutting, and resist wear better than the iron matrix, how is a softer steel going to hold a better edge? I've been able to get softer steels sharpened with less work and (without an electron microscope to make the comparison) they seemed as sharp as the harder steels, but heavy use - dressing game, cutting meat, hides, leather, etc. - required frequent touchups to maintain the edge. Every time I've used a cutting tool (machete, axe, sickle, sythe, etc.) it's been a softer steel and it always lost its edge with use. I didn't pay much attention to the particular steels used because they were cheap work implements often locally manufactured from scrounged materials with more art than science. On the other hand my Yarboro knife still has the factory edge and it will still shave anything that'll hold still long enough. Am I reading too much into this? Inquiring minds want to know - :munchin Peregrino

[Maytime]

...hardness is the resistance to penetration of the surface of a material by a hard object.


IIRC, hardness is tested with a small diamond punch and a machine that applies a given force, so afterwards you measure the depth of the protrusion (with a computer?). From there hardness is referenced in a big book of numbers or I suppose the computer can just tell you. Mr. Harsey can elaborate or correct me; he knows volumes more than I.

[Bill Harsey]

IIRC, hardness is tested with a small diamond punch and a machine that applies a given force, so afterwards you measure the depth of the protrusion (with a computer?). From there hardness is referenced in a big book of numbers or I suppose the computer can just tell you. Mr. Harsey can elaborate or correct me; he knows volumes more than I.
Maytime, You have already answered this correctly and I have already explained it further in the preceding text. We don't use computers in our Rockwell testers but just an old fashioned caveman analog dial.

Hardness is not the only characteristic which explains edge holding of which abrasion resistance is also a component.

[Bill Harsey]

OK - I'm sacrificing myself for the greater good. I don't normally throw myself on live grenades but this one I've got to see. What's confusing me is the definition of hardness. Rockwell #s aside, I thought hardness (as a factor in edge holding ability) was a function of % of carbon in the steel, the heat treat, and the resulting grain size and density of the carbides. Softer steel = fewer carbide crystals in the iron matrix. (Assuming a quality heat treat with controlled grain size/growth that doesn't leave the steel brittle and prone to cracking.) Since the exposed carbides (ideally troosite after martensite is converted during tempering) along the edge (earlier lecture on S30V) do the cutting, and resist wear better than the iron matrix, how is a softer steel going to hold a better edge? I've been able to get softer steels sharpened with less work and (without an electron microscope to make the comparison) they seemed as sharp as the harder steels, but heavy use - dressing game, cutting meat, hides, leather, etc. - required frequent touchups to maintain the edge. Every time I've used a cutting tool (machete, axe, sickle, sythe, etc.) it's been a softer steel and it always lost its edge with use. I didn't pay much attention to the particular steels used because they were cheap work implements often locally manufactured from scrounged materials with more art than science. On the other hand my Yarborough knife still has the factory edge and it will still shave anything that'll hold still long enough. Am I reading too much into this? Inquiring minds want to know - :munchin Peregrino

Looks like we better figure out simple knife shop and user definable hardness in tool steels before we go any farther and I will do that later.

There are knives harder than the Yarborough that will not hold an edge as long.

The answer to this can be found in the preceding text.:D
Edited to add:
Or maybe not, after review I note it was alluded to it but not explained.
Class?

[HOLLiS]

Most files are designed to cut steel and have a very high carbon content for maximum hardness. This makes them hard to work (make into a knife) and they tend to be brittle in hard use.

A better answer is yes they will make a good knife for some applications but the difficulty of working the file into a usable knife blade would put it down on my list of materials to use.

I knew it was in this folder somewhere.

[Bill Harsey]

Hollis, That's close but there's more than just Iron carbides in play here.

[Peregrino]

OK - I tried the "search" button and did a little deductive reasoning. Are we thinking in terms of exotic carbides e.g. the vanadium carbides in the S30V and the CPM154? As in the supporting iron matrix having a lower hardness number to give it greater toughness/shock resistance and the sharpness/edge holding characteristics being derived primarilly from the exotic carbides? As best I can grasp it - the only way to accomplish this is with the Crucible steels or some similar sintered metal process. :confused: Peregrino

[Bill Harsey]

OK - I tried the "search" button and did a little deductive reasoning. Are we thinking in terms of exotic carbides e.g. the vanadium carbides in the S30V and the CPM154? As in the supporting iron matrix having a lower hardness number to give it greater toughness/shock resistance and the sharpness/edge holding characteristics being derived primarilly from the exotic carbides? As best I can grasp it - the only way to accomplish this is with the Crucible steels or some similar sintered metal process. :confused: Peregrino
Peregrino, Pretty good thinking for a gunslin... Uh- I mean Good job.

Yes it is the hard carbides suspended in the matrix that give this steel and others like it the "high performance" edge holding.

A Rockwell hardness test involves the entire steel, matrix included and this test cannot show the hardness of the individual carbides.

Vanadium carbides are harder than the aluminum oxide that makes up sharpening stones. This is one of the carbides responsible for the high performance of the CPM S-30V steel.

Note, CPM S-30V is NOT a sintered metal even though a step in the manufacturing process might suggest that. It is a 100% solid steel.

[Bill Harsey]

The fastest simple time honored hardness test is to grab a steel cutting file and file on the work piece.

Most steel cutting files are in the Rockwell "C" Scale 62 range.
This means if the file cuts the test piece easy it is softer than R "C" 62.
If the file can't cut anything and just skids off the surface of the test piece, it is harder.
If one tests many pieces of tool steel this way it can become possible to "feel" the subtle differences.

Before I take my CPM S-30V blades to the Rockwell tester, I file them (carefully over the unsharpened edge) to see if I can guess the hardness.

The last time I did this almost caused panic because I thought I was going to have to do the heat treat over again for not being hard enough but the blades tested right at R "C" 58.5, right in the hard use hardness range we like.
There's a lesson in this story too.

[HOLLiS]

The fastest simple time honored hardness test is to grab a steel cutting file and file on the work piece.

Most steel cutting files are in the Rockwell "C" Scale 62 range.
This means if the file cuts the test piece easy it is softer than R "C" 62.
If the file can't cut anything and just skids off the surface of the test piece, it is harder.
If one tests many pieces of tool steel this way it can become possible to "feel" the subtle differences.

Before I take my CPM S-30V blades to the Rockwell tester, I file them (carefully over the unsharpened edge) to see if I can guess the hardness.

The last time I did this almost caused panic because I thought I was going to have to do the heat treat over again for not being hard enough but the blades tested right at R "C" 58.5, right in the hard use hardness range we like.
There's a lesson in this story too.

I have use the file test before, it is easy and often available to most people.

[Bill Harsey]

I have use the file test before, it is easy and often available to most people.
It will tell you a lot, like can I drill or machine this steel in this condition?

Did the heat treating make any changes, hopefully for the better?

[gunnerjohn]

I believe the answer to if you can drill or machine the steel in the hardened steel is maybe. If you have rigid enough of a set-up and properly designed tooling with TiAlN coating, you will be able to cut the hardened steel. You may not be able to work it very quickly and you may burn up some expensive tooling, but yes you can cut it. With some of the carbide drill bits you would be able to get into the surface some before the bit melts.

Note:
TiAlN coating is Titanium Aluminum Nitrite ceramic coatings applied the the surface of the carbide tool. This allows many steels to be cut like it was aluminum. The coatings actually "like" it when they get hot and have constant friction. It was developed for Boeing to ease the machining on all of the titanium and tool steels they use.

[Bill Harsey]

John, Great technical data but I wasn't making it that complicated.

I wanted to use the file to figure out if the steel in question was simply hard or soft.

[Bill Harsey]

Guys and Gals,
We've laid down enough stuff so far to make common folk hate reading about steel.
Good thing we don't have any common folk around here.

You've noticed in this thread that a concern when heat treating hardenable steels is cracking if we cool it too fast from the initial hardening temp. Welding heat can cause this too.

Here is a tip to lock down and print out for any of you guys and gals are out in the field that might have to make an emergency weld on unkown steels.

Pre-heat your weld zone (the steel) to 300 degrees F. Use your best judgment. Make the weld and if possible, post heat for a couple minutes with the same torch or heat source. DO NOT COOL WITH WATER!

This will greatly increase the chances of the weld not cracking on castings, shafts, springs, etc. Use 7018 Low Hydrogen rod on DC Reverse polarity of possible. If your welding on cases or around things that have bearings in them, place the ground clamp within 6 inches of the weld, either coming or going as the magnet will deflect the arc.

This stuff is so good I should charge money for it. :D

Edited to add:
AmbushMaster, I have no technical data on using various and interesting alternative heat sources for a controlled pre-heating of steel that may be readily available to the Special Forces Soldier.

[Ambush Master]

Guys and Gals,

This will greatly increase the chances of the weld not cracking on castings, shafts, springs, etc. Use 7018 Low Hydrogen rod on DC Reverse polarity of possible. If your welding on cases or around things that have bearings in them, place the ground clamp within 6 inches of the weld, either coming or going as the magnet will deflect the arc.

This stuff is so good I should charge money for it. :D

What do you think about "Square Wave" Machines?!?!:D

[Bill Harsey]

What do you think about "Square Wave" Machines?!?!:D
I've never had the privilege of welding with that type of welder. All my welding has been with "tough guy" welding machines that do not have the exotic manipulation of the electrical current that you big city kids like. :D :D

[LibraryLady]

Mr. Harsey,

You mentioned in another conversation, knife makers like the waterjet vs the laser as there's no heat residual when working with the high end "tough stuff". So if you cut the knife blank, (and I'm assuming you do this first) then go through the Martensitic Transformation process, won't that negate any of the heat issues from the laser? Or does repeated applications of heat affect the carbon atom structure development?


LL

[Peregrino]

Mr. Harsey,

You mentioned in another conversation, knife makers like the waterjet vs the laser as there's no heat residual when working with the high end "tough stuff". So if you cut the knife blank, (and I'm assuming you do this first) then go through the Martensitic Transformation process, won't that negate any of the heat issues from the laser? Or does repeated applications of heat affect the carbon atom structure development?


LL


Looks like we're going to have to watch this one. She lurks quietly for "a while", does her homework before posting, follows the rules, and all of a sudden - out of left field, detonates a claymore. Got to watch them librarian types - the ones I know suffer from insatiable curiosity and a true "garbage collector" mentality (always learning little bits and pieces "cause you never know when it might be useful"). Nice question though. I wouldn't mind knowing the answer to that one myself. JFTFOI - Peregrino

[Bill Harsey]

Mr. Harsey,

You mentioned in another conversation, knife makers like the waterjet vs the laser as there's no heat residual when working with the high end "tough stuff". So if you cut the knife blank, (and I'm assuming you do this first) then go through the Martensitic Transformation process, won't that negate any of the heat issues from the laser? Or does repeated applications of heat affect the carbon atom structure development?


LL
LL, You ask a very good question and I agree with Peregrino.
Here is answer:
First, your correct that the heat treat process could overcome some of the change in hardnesses caused by the lasers heat as it profiles out a knife blank from the parent stock.

The kind of problem we have seen when laser cutting heat sensitive air hardening tool steels cannot be solved by any type of annealing or heat treatment.

Tool steels are broadly categorized according to which medium (water, oil, air)
they need to be quenched in for full hardness. The more highly alloyed a tool steel, the "deeper" it heat treats and the slower it can be cooled for full hardness. This means "air quench" steels cool faster and do not have to be driven as hard in a cooling medium to be fully hardened.
Water hardening tool steels are shallow hardening and must be quenched in water to "drive" the temp down as fast as possible to get full hardening.
The opposite of water hardening tool steels are Air Quench, these steels cool faster on their own and are usually quenched from the high austenitizing heat in still or fan blown air. If you quenched the air hard stuff in water, the steel would break or shatter from the stress of cooling.

The problem we have with laser cutting happens very fast and cannot be repaired.
When laser cutting air-hard tool steels like CPM S-30V sometimes the laser guy doesn't pay attention to the correct sequence of the CNC tool path (the path the laser travels) the knifemakers have called out and there will be some over heating in a thinner area and this will cool fast enough that a crack develops.
This crack is then later found after much labor has been invested in the blade which results in the that piece of work being discarded.

The reason we have switched to the more costly process of waterjet cutting is because it's a "cold" process. Water jet cutting uses extremely high water pressure of around 50,000 PSI thru an orifice about the diameter of a pencil lead combined with garnet and is guided by CNC controls just like the laser.
There is effectively zero heat build up in water jet so no cracking from extreme surface heat happens.

[LibraryLady]

Thank you for the response, Mr. Harsey

Nice to know I was at least partially correct. And your further explanation satisfied my insatiable curiosity as to why you’d choose the more expensive waterjet over laser. Now it’s back to my other homework. I'll have to save further perusal of this process for awhile.

The rule-abiding, garbage-collecting left field claymore-detonating lurker. snicker

LL

[Bill Harsey]

Thank you for the response, Mr. Harsey

Nice to know I was at least partially correct. And your further explanation satisfied my insatiable curiosity as to why you’d choose the more expensive waterjet over laser. Now it’s back to my other homework. I'll have to save further perusal of this process for awhile.

The rule-abiding, garbage-collecting left field claymore-detonating lurker. snicker

LL
Your welcome, we had been putting the laser cut blade blanks into an annealing cycle directly after cutting and we still got a few cracks from the laser.
This is how we learned where the problem was and annealing wouldn't solve it.

[Maytime]

Mr. Harsey,
Does your waterjet machine use the grains of sand to cut, or is it purely water?

Also, I was thinking about the heating problems with laser cutting and thought, why not cool the piece as you cut? Any liquid with an index of refraction not equal to 1 is out of the question, since the laser beam would be bent, so what about air cooling? Is it possible to cool the piece precisely as the beam would heat it up, to maintain a "cool"-like process?

[Bill Harsey]

Mr. Harsey,
Does your waterjet machine use the grains of sand to cut, or is it purely water?

Also, I was thinking about the heating problems with laser cutting and thought, why not cool the piece as you cut? Any liquid with an index of refraction not equal to 1 is out of the question, since the laser beam would be bent, so what about air cooling? Is it possible to cool the piece precisely as the beam would heat it up, to maintain a "cool"-like process?
Maytime, Answer to "grains of sand" is in the above text.

Water would only make the problem much worse by causing a **super heated at the edge by laser cut** air hardening tool steel to be quenched in water as it was being cut.

Re-read the part about the difference bewteen water-oil-air hard steels. This is not abstract theory.

[Q]

OOPs, backin' up here. Wrong thread.

[Bill Harsey]

OOPs, backin' up here. Wrong thread.
C'mon Q,
Think of something...please?

[Q]

Howdy Bill. Yeah I've gotta find a discreet folder that be quick. I like what I read about the D-2. Do you have any others out there I'm unaware of?

Q, I'll send ya a pm. Bill Harsey

[Bill Harsey]

The main thing a hard use knife has to do is cut.

To do this a knife has to be able to be sharpened, take a fine edge and hold up to some abuse without that edge rolling over, chipping or breaking.
The opposite of this is to make a very thick blade that can stand up to heavy pry bar use but these don't cut that well and can be very difficult to sharpen.

Cutting can be fine work with hand pressure or chopping as hard as the user can swing it.

In any given steel we can modify the thickness of the blade and the geometery of the grind to make it cut very well on fine work or stand up to the severe uses.

The closer a knifemaker wants to "dial in" a knife for both uses, the more important the quality of the steel and the heat treat become. This applies to all tool steels used for making knives.

[Bill Harsey]

A few days ago I was asked by a member of our military (not a ps.com member) why we and others use CPM S-30V for our military use knives.

My answer was to read here and after re-reading this thread realized I haven't stated why.

Here is the short version:
CPM S-30V has 2 to 3 times the bend fracture or pry bar strength of the old 154CM which we used to use a lot of. The "old" 154CM is still good stuff too.

Because of how the steel is made the grain structure is much finer than conventional tool steels resulting in a much higher degree of intial sharpness.

This means if I do the same sharpening on this steel and another,
the CPM S-30V comes up sharper.

The CPM S-30V contains both carbides and nitrides in the grain structure and has greater wear resistance at a lower Rockwell hardness than some other knife tool steels at a higher Rockwell hardness.

Also note as I have stated before, many great knives are made from many types of steel. This is just what we do.

[The Reaper]

Bill:

Any comments on when S3V might be a better material?

TR

[Bill Harsey]

Bill:

Any comments on when S3V might be a better material?

TR

CPM S-3V has the same abrasion resistance (edge holding) as CPM S-30V but double the impact strength. S3V has little or no stain resistance.

The "double impact strength" would make it a very good candidate for impact tools such as an axe bit.
I have not yet worked with S-3V mainly because of the lack of stain resistance.

Stain resistance is what keeps a blade from losing its edge in some conditions like warm and humid or marine environments.

[jdl141]

Bill,

Have a question for you. Between the stainless steel that Randall Knives use and the CPM S30V stainless steel used in the Pacific knife, what are the major differences?

Thanks,

Jim

[Bill Harsey]

Bill,

Have a question for you. Between the stainless steel that Randall Knives use and the CPM S30V stainless steel used in the Pacific knife, what are the major differences?

Thanks,

Jim

Good question, Thank you.

First please let me do some homework and see if I can make sure what knife steel the Randall knife shop is using. Last time I did a cursory check of their website I didn't see the alloy listed.

[jdl141]

Thanks Bill. I have a Randall Model 14 in Stainless. I purchased this knife around 1989.

[zeke]

Mr. Harsey,
For your heat treating of steels after making a blade, could you use a pottery kiln opposed to a specific heat treating furnace, or is there a need for finer temperature control? It seems that pottery kilns are easily found used on craigslist and would save some money.

[Sean King]

Can someone tell me how D2 steel compares to say ATS-34/154-CM in terms of overall strength and durability and ability to hold and edge, sharpen, etc?

I know D2 is not really considered stainless, it doesn't usually have a great looking finish, and has excellent edge holding....but I'm not sure how tough it is or how it's edge holding and difficulty in sharpening is when compared with 154-CM.

I guess what I'm getting at is if you had to choose between two identical knives with these two steels, which would you choose and why?

Any insight is appreciated.

Thanks,
Sean

[The Reaper]

Can someone tell me how D2 steel compares to say ATS-34/154-CM in terms of overall strength and durability and ability to hold and edge, sharpen, etc?

I know D2 is not really considered stainless, it doesn't usually have a great looking finish, and has excellent edge holding....but I'm not sure how tough it is or how it's edge holding and difficulty in sharpening is when compared with 154-CM.

I guess what I'm getting at is if you had to choose between two identical knives with these two steels, which would you choose and why?

Any insight is appreciated.

Thanks,
Sean

Sean:

You are starting to become an annoyance.

From your posts thus far, it appears to me that you do not like to read, follow rules, or do your own research.

The Search button is your friend.

Stop starting new threads and asking questions you have not yet researched thoroughly.

TR

[Sean King]

Sean:

You are starting to become an annoyance.

And frankly, so are you. What have I done specifically to wrong you personally? Yes, I didn't do a proper introduction when I posted here for the first time. I acknowledged my error, corrected it and then apologized for it. What else is required? Let me know, and I'll try to accomodate your request. If it's that I search more....I did....and I'll explain that shortly.

You've now started what can only be termed a 'witchhunt' about my 'searching' judging by your post in the "Harsey on the Beach" thread and now this one.

Well, let's just lay it all out on the table and you can go about banning me after if you'd like. But, I WILL say my piece.


From your posts thus far, it appears to me that you do not like to read, follow rules, or do your own research.

The Search button is your friend.

Stop starting new threads and asking questions you have not yet researched thoroughly.

TR

First of all, I didn't START a new thread. In fact, I haven't started ANY threads. I replied to an exsisting one. There's a difference. You're making it seem as if I'm going around the board starting new threads asking questions that have already been asked and that's neither a fair representation or at all accurate.

Second, this thread is titled: "Knife Steels-Material Science" and would therefore be a good place to post a question discussing the merits of one steel versus another for comparison purposes, don't cha think?? :confused:

Third, there are only a very few posts (specifically #38-41) that even really discuss ANYTHING about D2 steel in this thread (we'll get to other threads in a moment). I read this thread a few days ago before I posted in this one at all. I just re-read it again, to see if your accusations had any merit. They do not. My questions were not covered, so I asked. I was taught that the only stupid question is the one you don't ask....if I don't ask, I won't learn anything, especially using this search engine (more on that later as well).

Fourth, nowhere in this thread is CPM154 (or 154-CM if you prefer) and D2 steel directly compared; which is why I posted in this thread in the first place. Isn't a question like mine something someone might want to know in the future? Wouldn't a search pop up this thread and help someone else find the answer? I did search. Where do you think I came up with "...D2 is not really considered stainless, it doesn't usually have a great looking finish, and has excellent edge holding..."? Part of it is from what I read here as well as what I researched on the net. And yes, before you go off on my reading comprehension....I realize that you and Mr. Harsey discussed the carbide size requiring a thicker edge, and is therefore harder to get really sharp, but Mr. Harsey still said, "D-2 is a legitimate knife blade steel." and commented that he could still make very good knives from it. What I didn't get from your discussion was any reference point about CPM154 vs. D2. Can you understand where I'm coming from?

Fifth, perhaps my search foo is weak? :D This search engine leaves a LOT to be desired. Instead of giving hits on specific posts where the search term is used, it gives entire threads. These threads can be several pages long and it doesn't highlight the search term other than bolding it in white....not very conducive to finding information compared to other software. For example, when I search D2 steel, or D2 vs CPM154 or D2 vs 154-CM using the normal or advanced search engine on this site, I get all kinds of threads....but none of the thread titles short of this one would give any indication that D2 steel vs. CPM154 is the topic of the discussion (and to be fair, this one doesn't either...but it is the most likely one in which material differences would be the topic of conversation). Since I had read the whole thread (twice now) can you recommend a thread I should've looked at for this specific comparison? I didn't even see any with the term "D2" in the title.

Sixth, post number 118 is essentially a similar question to my own....but you didn't jump that poor guy for asking it. Why? He's asking the difference between his Randall's stainless steel and CPM-S30V. What's the difference betwen his comment and my own?

Seventh, you knew darn well that I wouldn't be able to search for the "pepper" reference I innocently asked about in the Harsey on the Beach thread. Yet you baited me with the question about "search button not working?". I responded as curteously as I could, when I was pretty sure that your tone was not a friendly one just as this latest volley wasn't.

My attitude is a direct reflection of your tone. I understand that the written word is a hard medium to convey meaning without misinterpretations, but how else am I supposed to take your comments to me?

Look, you've taken a dislike to me. I get it. I'm not sure why, but whatever. I'm reasonably sure you'll say you really don't care and neither do I. I actually enjoy your little jabs at my expense. It's interesting to probe the psyche of someone like you.

Let me tell you a little about me now....you might as well ban me (if you have the power) or get me banned by someone who does.....not because I'm going to be rude but b/c I just will not drop the issue. I am the most stubborn person you'll ever have the misfortune of meeting. :D I didn't do anything wrong by asking about "peppers" and I didn't do anything wrong by asking about the differences in two knife steels in this, a knife steel material science thread, and I will not budge on that. Say what you will and ban me if you must. I know whatever you can muster up as "punishment" is really irrelevant anyway....this is just the internet.


Lastly, the easiest way to shut me up (short of banning me) is to ignore me. JFYI.

If this is the last time I'm allowed to post, have a nice life. If, on the other hand, you want to discuss this further, reply here or PM me....as I'm sure this wasn't the appropriate place for this commentary and it will be deleted, but I thought it only fair that I be given the same public opportunity to rebutt your allegations.

Good day,

Sean King

[The Reaper]

126 Search hits for knife steels.

This is among the first, there are many more, most in this forum:

http://www.professionalsoldiers.com/forums/showthread.php?t=704&highlight=knife+steel

Not reading these threads before asking indicates laziness to me, and your post above a disrespect for authority. Your stubbornness will not be an asset here.

Most of the people on this board have better things to do than to rehash the same topics repeatedly, because you want personal attention. The best thing to do when you realize that you are in a hole is to stop digging.

There is a lot of info here, for those willing to look for it.

The only allegation in my comments was that you do not like to read, follow rules, or do your own research. I stand by that assessment.

This is not your board, you are a guest here. Think about it.

No response is necessary.

TR

[Team Sergeant]

And frankly, so are you. What have I done specifically to wrong you personally? Yes, I didn't do a proper introduction when I posted here for the first time. I acknowledged my error, corrected it and then apologized for it. What else is required? Let me know, and I'll try to accomodate your request. If it's that I search more....I did....and I'll explain that shortly.

You've now started what can only be termed a 'witchhunt' about my 'searching' judging by your post in the "Harsey on the Beach" thread and now this one.

Well, let's just lay it all out on the table and you can go about banning me after if you'd like. But, I WILL say my piece.




First of all, I didn't START a new thread. In fact, I haven't started ANY threads. I replied to an exsisting one. There's a difference. You're making it seem as if I'm going around the board starting new threads asking questions that have already been asked and that's neither a fair representation or at all accurate.

Second, this thread is titled: "Knife Steels-Material Science" and would therefore be a good place to post a question discussing the merits of one steel versus another for comparison purposes, don't cha think?? :confused:

Third, there are only a very few posts (specifically #38-41) that even really discuss ANYTHING about D2 steel in this thread (we'll get to other threads in a moment). I read this thread a few days ago before I posted in this one at all. I just re-read it again, to see if your accusations had any merit. They do not. My questions were not covered, so I asked. I was taught that the only stupid question is the one you don't ask....if I don't ask, I won't learn anything, especially using this search engine (more on that later as well).

Fourth, nowhere in this thread is CPM154 (or 154-CM if you prefer) and D2 steel directly compared; which is why I posted in this thread in the first place. Isn't a question like mine something someone might want to know in the future? Wouldn't a search pop up this thread and help someone else find the answer? I did search. Where do you think I came up with "...D2 is not really considered stainless, it doesn't usually have a great looking finish, and has excellent edge holding..."? Part of it is from what I read here as well as what I researched on the net. And yes, before you go off on my reading comprehension....I realize that you and Mr. Harsey discussed the carbide size requiring a thicker edge, and is therefore harder to get really sharp, but Mr. Harsey still said, "D-2 is a legitimate knife blade steel." and commented that he could still make very good knives from it. What I didn't get from your discussion was any reference point about CPM154 vs. D2. Can you understand where I'm coming from?

Fifth, perhaps my search foo is weak? :D This search engine leaves a LOT to be desired. Instead of giving hits on specific posts where the search term is used, it gives entire threads. These threads can be several pages long and it doesn't highlight the search term other than bolding it in white....not very conducive to finding information compared to other software. For example, when I search D2 steel, or D2 vs CPM154 or D2 vs 154-CM using the normal or advanced search engine on this site, I get all kinds of threads....but none of the thread titles short of this one would give any indication that D2 steel vs. CPM154 is the topic of the discussion (and to be fair, this one doesn't either...but it is the most likely one in which material differences would be the topic of conversation). Since I had read the whole thread (twice now) can you recommend a thread I should've looked at for this specific comparison? I didn't even see any with the term "D2" in the title.

Sixth, post number 118 is essentially a similar question to my own....but you didn't jump that poor guy for asking it. Why? He's asking the difference between his Randall's stainless steel and CPM-S30V. What's the difference betwen his comment and my own?

Seventh, you knew darn well that I wouldn't be able to search for the "pepper" reference I innocently asked about in the Harsey on the Beach thread. Yet you baited me with the question about "search button not working?". I responded as curteously as I could, when I was pretty sure that your tone was not a friendly one just as this latest volley wasn't.

My attitude is a direct reflection of your tone. I understand that the written word is a hard medium to convey meaning without misinterpretations, but how else am I supposed to take your comments to me?

Look, you've taken a dislike to me. I get it. I'm not sure why, but whatever. I'm reasonably sure you'll say you really don't care and neither do I. I actually enjoy your little jabs at my expense. It's interesting to probe the psyche of someone like you.

Let me tell you a little about me now....you might as well ban me (if you have the power) or get me banned by someone who does.....not because I'm going to be rude but b/c I just will not drop the issue. I am the most stubborn person you'll ever have the misfortune of meeting. :D I didn't do anything wrong by asking about "peppers" and I didn't do anything wrong by asking about the differences in two knife steels in this, a knife steel material science thread, and I will not budge on that. Say what you will and ban me if you must. I know whatever you can muster up as "punishment" is really irrelevant anyway....this is just the internet.


Lastly, the easiest way to shut me up (short of banning me) is to ignore me. JFYI.

If this is the last time I'm allowed to post, have a nice life. If, on the other hand, you want to discuss this further, reply here or PM me....as I'm sure this wasn't the appropriate place for this commentary and it will be deleted, but I thought it only fair that I be given the same public opportunity to rebutt your allegations.

Good day,

Sean King


For a supposed engineer you ain't too smart. When you hit the "search" button it gives you two options, "show threads" or "show posts", if you're having a hard time reading let me know.

And for your information the Reaper has the means to ban you in in a Texas heartbeat, that he already didn't must mean he's killed something today and has already satisfied that urge.

If he doesn't end up banning you I probably will. It also seems you didn't read the introductions thread either..... I've highlighted something that should interest you...

"What Professional Soldiers ® is - The first thing to understand is that site is directed primarily to the Special Forces Soldier, and those interested in the SF life-style. It is our site and if you are not a member of the Special Forces, you are a guest. We welcome discussion - we demand respect be shown to all members and we will show you the same, provided you demonstrate you deserve. Respect is earned not decreed."

http://www.professionalsoldiers.com/forums/announcement.php?f=68

Board rule #7;

7. Think before you post. Post something unintelligent and we’ll let you know. Post something unintelligent twice and you’ll be gone. We ask no quarter and none will be given.

http://www.professionalsoldiers.com/forums/showthread.php?t=3452

Mouth off again and you are gone.

Team Sergeant

[Team Sergeant]

Stupid is as stupid does.

Goodbye Sean King.

Team Sergeant

[Arwr]

Randall Made Knives use O1 carbon and 440 stainless steels.

Arwr

[Bill Harsey]

Randall Made Knives use O1 carbon and 440 stainless steels.

Arwr
Both those steels can be made into very good knives.
You'd have to contact the Randall Shop to confirm what steels they are using.
They may be up to more than we know.

[FMF DOC]

Some help please, I didn't want to start a new thread and this looked like it was on target...

Could someone explain to me the difference between the grades or makes of steel ie: 440c 50, 57-59 HRC ect ect ect... looking to buy a good quality fixed blade but never did understand what was good and what was cheaply made.:confused:

Thanks in advance for your input...

[Ambush Master]

You can't go wrong with CPM S30V!! Google it.

This is the steel that the Yarborough is made of.

Later
Martin

[Bill Harsey]

FMF Doc,
I'm trying hard to not advocate one steel or another here because that gets into whose work I may be seen as promoting or not and that is not my reason for being here.

Martin, Thanks! yes we use the CPM S-30V in the Yarborough knife and I really believe in that alloy produced by Crucible Steel here in the USA.

Many steels can make a good knife but this depends on if the given steel is heat treated for it's optimum use and what price one is willing to pay for that particular tool. Reputation of maker/manufacturer is important as any steel is only as good as it's optimum heat treat combined with blade geometery.

You can have the perfect steel and perfect heat treat but if the blade is too thin or too thick it will not function as needed. A good using knife is a combination of factors. Please forgive me for stating the obvious.

[Bill Harsey]

Some help please, I didn't want to start a new thread and this looked like it was on target...

Could someone explain to me the difference between the grades or makes of steel ie: 440c 50, 57-59 HRC ect ect ect... looking to buy a good quality fixed blade but never did understand what was good and what was cheaply made.:confused:

Thanks in advance for your input...
I'm re-reading thread to see if this some of this question has been answered or not.

[FMF DOC]

Ok, can some let me know how good or bad the specs on this blade are.

Stailess Steel 55-57 HRC hardness rated 6 3/4 I and is 9 2/5 ozs and 11 in overall, or is this just a cheap blade. I realize you get what you pay for and this knife priced for less than $100.00 I'm just looking for something I can use to beat around, maybe carry in the tool box as an extra.

Thanks

[Bill Harsey]

Ok, can some let me know how good or bad the specs on this blade are.

Stailess Steel 55-57 HRC hardness rated 6 3/4 I and is 9 2/5 ozs and 11 in overall, or is this just a cheap blade. I realize you get what you pay for and this knife priced for less than $100.00 I'm just looking for something I can use to beat around, maybe carry in the tool box as an extra.

Thanks

Sir,
Can you pm me more information on the knife in question? I will respond via pm also.
Thanks, Bill

[x SF med]

Bill,
Let me recap the last 2 hours of reading; the Boss is at work, and I walked away from work long enough to really digest the the amazing information in this thread.

1. there are a whole spate of excellent knife steels out there
2. use is a primary consideration in the steel selection
3. 'stainless' does not mean it won't 'rust'
4. The matrix size directly affects the sharpness and possibly the durability of of the edge
5. the addition of various other metals, salts, and nonmetals can directly affect matrix size of the finished product (chemically and physically)
6. The metal continues to change throughout the working process, and that process is tailored to the metal itself so that the physical and chemical changes are going in the correct direction.
7. heat is good, heat is bad
8. cold is good, cold is bad
9. there are changes in the metal during the working process that cause a 'grain' i.e. austentising, martensiting, etc. in the blade itself and this grain is dependent on the annealing, heating, cooling and original chemical (what's in there)/physical (matrix size)/temporal (how long heated and cooled, and change in temperature over time of change)
10. the most exposed area of the metal (actually the sharpened edge) is also the area that is most dependent on the 'stainless' capabilities of the blade - as the atmospheric conditions may cause salts to form that will dull the edge by chemical breakdown.
11. hardness is good, hardness is bad
12. matrix size affects the edge holding and ultimate sharpness of the edge

13. I need to reread this thread to find out how much I missed and still don't know.

and finally - you really are a lot smarter than you look, your depth of knowledge amazes me - even about music - but you really need to change that one light bulb in the shop stereo.

[Ambush Master]

Bill,
Let me recap the last 2 hours of reading; the Boss is at work, and I walked away from work long enough to really digest the the amazing information in this thread.

13. I need to reread this thread to find out how much I missed and still don't know.

and finally - you really are a lot smarter than you look, your depth of knowledge amazes me - even about music - but you really need to change that one light bulb in the shop stereo.

All of the ABOVE but, #13 Kind'a says it ALL!! The answer to #13 is INFINITESIMAL!!!!

Take care Brother!!!:D
Martin

[Bill Harsey]

x SF med,
I really like your take on things, you speak many truths in ways I would not have thought of.
Will look forward to discussing details after the trip to Atlanta.

Thank you for the kind words.

[x SF med]

x SF med,
I really like your take on things, you speak many truths in ways I would not have thought of.
Will look forward to discussing details after the trip to Atlanta.

Thank you for the kind words.


Bill, Martin-
Thanks!
I went back through my list after a little sleep, and realized the list above, almost gets one to the point where you can design the blade once you figure out how the knife is going to be used.
The design of the knife; edge versus spine thickness; shape of the edge(s); length, depth, breadth of tang; known treating/annealing properties of the metal; re-matrixing; and the grain of the martensiting/austensiting ... may cause reconsideration of the steel used after the prototype is underway, based on the production capabilities if the blade is going into mass, or even in some cases limited production, just from the QC process on each blank prior to final edge shaping and sharpening.

Bill... in the words of my concrete busting and pouring buddy, you really just might be a rocket surgeon - I gain more and more respect for you, your craft, the art and the science of your designs the longer I know you.

[Herdbull]

I am looking at a leatherman Supertool 300 to replace a leatherman I lost over the weekend. I noticed the blade is 420 HC steel as opposed to 154 CM or S30V that you see on some other tools. This tool will see some pretty hard use (farming hunting camping)

Can you tell me about 420 HC? how does it compare? major differences?

Thanks

[Trip_Wire (RIP)]

I went to my old Tac-30 (SWAT) teams annual banquet dinner the other night and a member of the team had made knives with a Kydex scabbard, with engraving on them for people leaving the team. I liked the knife and asked him to make one for me. He does 'Black Dog Knives.' He is/was also a team member and KCSO Deputy.

He said "It will be made from ATS-34, with micarta scales and will include a custom Kydex sheath. " $100 Plus Tax & engraving ($25) depending on the number of letters.

He'll engrave the following on the knife as well as the SWAT Logo.

LT. My Name
TAC-30 Founding Member
1968-1984

The knives that I looked at did look good and had nice thick blade. Is that ATS-34 a good choice? The blade shape looked like a larger version of my PS knife.

[Bill Harsey]

I am looking at a leatherman Supertool 300 to replace a leatherman I lost over the weekend. I noticed the blade is 420 HC steel as opposed to 154 CM or S30V that you see on some other tools. This tool will see some pretty hard use (farming hunting camping)

Can you tell me about 420 HC? how does it compare? major differences?

Thanks

420HC is a medium carbon good working blade steel that is fairly stainless. The quality of any given blade steel is only as good as it's optimum heat treat and I have no knowledge of how these are done.

When all heat treated correctly for knife use 420HC does not have quite the edge holding of 154CM and the next rung up the edge holding ladder is CPM S-30V.

[Bill Harsey]

The knives that I looked at did look good and had nice thick blade. Is that ATS-34 a good choice? The blade shape looked like a larger version of my PS knife.

ATS-34 is a very good knife steel. Here is how it came into existence:

First, it was Bob Loveless who revolutionized modern knife making with both his designs and dedication to testing alloys of tool steels for knife use.

Loveless found a very high grade of tool steel produced by Crucible Specialty Tool Steels in Syracuse New York called 154CM. This was a big jump forward in knifemaking as it was both a high performance steel and has good stain resistance.

Crucible at that time was owned by Colt Industries. Loveless was having some problems sourcing the steel from them, forget if it was pricing or something else but the result was Loveless going to Japan, founding the Japanese Knifemakers Guild on the way, meeting the president of Hitachi Steel and asking him to make a steel with "about the same" ;) chemical composition as 154CM and the result is ATS34 which I have used a lot of in the past.
It's good steel.

[The Reaper]

Thanks, Bill.

IIRC, Al Mar used quite a bit of ATS34 as well.

TR

[Trip_Wire (RIP)]

ATS-34 is a very good knife steel. Here is how it came into existence:

First, it was Bob Loveless who revolutionized modern knife making with both his designs and dedication to testing alloys of tool steels for knife use.

Loveless found a very high grade of tool steel produced by Crucible Specialty Tool Steels in Syracuse New York called 154CM. This was a big jump forward in knifemaking as it was both a high performance steel and has good stain resistance.

Crucible at that time was owned by Colt Industries. Loveless was having some problems sourcing the steel from them, forget if it was pricing or something else but the result was Loveless going to Japan, founding the Japanese Knifemakers Guild on the way, meeting the president of Hitachi Steel and asking him to make a steel with "about the same" ;) chemical composition as 154CM and the result is ATS34 which I have used a lot of in the past.
It's good steel.

Thanks Bill! :)

[NOQUIT]

Thank you for this thread Mr. Harsey, it's a great read. Being a knife lover the chemical make up of blade steel has fascinated me. GO CPM S30 V! :D I especially like your explanations on what goes on at the molecular level during the heating and cooling processes with respects to freezing it in the ideal configuration. I hope this is even relevant but it made me think of a time I was fortunate enough to have a plane ride next to a guy that worked with NASA in the carbon fiber area and he was explaining to me (among other fascinating things) the differences in the molecular structure of a diamond carbon molecule as opposed to the I guess you could say "spun fiber" carbon molecule (carbon fiber) they use (not your average carbon fiber) as well as the individual strengths. What are your thoughts on or what have you heard/read about the possible applications of such molecular manipulation of carbon molecules for the making of blades? Not sure if I'm out in left field with this... I was also wondering if you have any knowledge of the OU-31 steel that Kikuo Matsuda employs and what your take is? I love the look of his work but haven't foot the bill for one yet. Thanks again for the great thread.

[Odikter]

Well, after hours of reading this post I still don't know how you choose the material if you like a shape of a knife for ex. in a web shop. Many knife brands choose the material for the knife instead of you for the use of the knife they make. Many steel producers make almost the same steel material in different names. Uddeholm, Böhler, etc. are famous steel factories and most of knife makers are choosing from they steels according the meaning of the knife. I am a knife maker too and also I am choosing different material for an assault knife than the survival one. Assault knife I make harder for ex. around 62 HRC, survival knives I make around 58 HRC just for easy sharpening in field. Harder material harder to sharpen but the edge takes longer, and via. So, I mean if you order knife from knifemakers they will offer from they available materials the best for your needs, but if you fall in love with a knife on the internet you have no chance to choose, just if you order a copy from a maker. I say that if the blade is for fight choose material around 62-63 HRC (never go over, may break in field) or if the blade is for common knife use search for 58-59 HRC hard material. No meaning for the name of steel. My best blades I made from recycled materials. (ball bearings, car springs, chainsaw chain) Good heat treating is the most necessary, the best material could be bad without a good heat treating.

The points of choosing knife (and material): hardness, stainless -or not, shape (full tang I prefer) and thickness, sharpening and cleaning attributes, handle material, love it or not. That simple. Would it be the hardest and greatest material if you cannot sharpen by yourself. (There is another knowledge for sharpening...)

There is no best steel material for knives, just difference for uses.

There is no bad knife, just bad hand for it...

Bill, this is not for You, I know You know all about that.
Sorry for the poor english...

[ld08]

Gentlemen,

I want to personally thank everybody who contributed to this topic! As a senior materials engineering student, this information has been invaluable to some real world scenarios and examples of materials science at work. Progressing through the pages of pure gold here, "I now know what I don't know"..

V/R
LD

[Bill Harsey]

Well, after hours of reading this post I still don't know how you choose the material if you like a shape of a knife for ex. in a web shop. Many knife brands choose the material for the knife instead of you for the use of the knife they make. Many steel producers make almost the same steel material in different names. Uddeholm, Böhler, etc. are famous steel factories and most of knife makers are choosing from they steels according the meaning of the knife. I am a knife maker too and also I am choosing different material for an assault knife than the survival one. Assault knife I make harder for ex. around 62 HRC, survival knives I make around 58 HRC just for easy sharpening in field. Harder material harder to sharpen but the edge takes longer, and via. So, I mean if you order knife from knifemakers they will offer from they available materials the best for your needs, but if you fall in love with a knife on the internet you have no chance to choose, just if you order a copy from a maker. I say that if the blade is for fight choose material around 62-63 HRC (never go over, may break in field) or if the blade is for common knife use search for 58-59 HRC hard material. No meaning for the name of steel. My best blades I made from recycled materials. (ball bearings, car springs, chainsaw chain) Good heat treating is the most necessary, the best material could be bad without a good heat treating.

The points of choosing knife (and material): hardness, stainless -or not, shape (full tang I prefer) and thickness, sharpening and cleaning attributes, handle material, love it or not. That simple. Would it be the hardest and greatest material if you cannot sharpen by yourself. (There is another knowledge for sharpening...)

There is no best steel material for knives, just difference for uses.

There is no bad knife, just bad hand for it...

Bill, this is not for You, I know You know all about that.
Sorry for the poor english...

Odikter,
Sorry for the delay in responding, very bad manners on my part.

Welcome to the knife area and if you would like, please post pictures of some of your knives here. I would like to see them.
Your english is much better than my Finnish or Sami.

We will talk more about steel hardness soon.

[Bill Harsey]

Gentlemen,

I want to personally thank everybody who contributed to this topic! As a senior materials engineering student, this information has been invaluable to some real world scenarios and examples of materials science at work. Progressing through the pages of pure gold here, "I now know what I don't know"..

V/R
LD

Your very, humbly, welcome.
Good news we haven't screwed up your work yet too.

We have access to a few metallurgists if you might need more help.

[Bill Harsey]

Thank you for this thread Mr. Harsey, it's a great read. Being a knife lover the chemical make up of blade steel has fascinated me. GO CPM S30 V! :D I especially like your explanations on what goes on at the molecular level during the heating and cooling processes with respects to freezing it in the ideal configuration. I hope this is even relevant but it made me think of a time I was fortunate enough to have a plane ride next to a guy that worked with NASA in the carbon fiber area and he was explaining to me (among other fascinating things) the differences in the molecular structure of a diamond carbon molecule as opposed to the I guess you could say "spun fiber" carbon molecule (carbon fiber) they use (not your average carbon fiber) as well as the individual strengths. What are your thoughts on or what have you heard/read about the possible applications of such molecular manipulation of carbon molecules for the making of blades? Not sure if I'm out in left field with this... I was also wondering if you have any knowledge of the OU-31 steel that Kikuo Matsuda employs and what your take is? I love the look of his work but haven't foot the bill for one yet. Thanks again for the great thread.

NOQUIT,
Wow, good plane ride!
My only experience with carbon fiber is to cut, drill and grind then complain when some chunk of it came from aerospace because it is much tougher to cut, drill and grind.
I have no knowledge of the OU-31 steel and this does not mean it isn't good steel.
As Oditker points out, there are many manufacturers of tool and bearing quality steels and each make many alloys.
We have to find ways to shorten up the list we draw from but it doesn't mean we aren't paying attention.

[greyfox]

Mr. Harsey,

Like many people who have posted before me, I am intrigued by the material science and engineering aspects of knife manufacturing. Reading through my texts books and pages in this thread, I'm beginning to realize that I now know much less than previously realized.

After using the search button, I could not find any information located on this website about the matter; I am curious, if metallic glasses (or bulk metallic glasses in particular) have ever been a viable option for knife design?

[Bill Harsey]

Mr. Harsey,

Like many people who have posted before me, I am intrigued by the material science and engineering aspects of knife manufacturing. Reading through my texts books and pages in this thread, I'm beginning to realize that I now know much less than previously realized.

After using the search button, I could not find any information located on this website about the matter; I am curious, if metallic glasses (or bulk metallic glasses in particular) have ever been a viable option for knife design?

greyfox,
Often I feel like I don't know enogh to have gotten this far and also ask a couple of good metallurgists, like the one who developed CPM S-30V, to review my writing here to make sure I'm not screwing up.

Haven't yet heard of metallic glasses being used for knifemaking. I know that there are ceramic blades, ruby, obsidian and glass with some modern applications.

If there is anything better than steel for making a knife out of, haven't heard about it yet.

Yes there are materials that get sharper than steel, like obsidian but obsidian has very little resistance to fracture or "toughness'.

Some good ceramics have much more fracture resistance than obsidian but are still subject to catastrophic failure when used hard.

Also of note, any material we use has to be relatively affordable. If something starts costing hundreds (or more) dollars per lb. Then we have another problem.

Some can take a broken glass window and make something that will open an animal and get to the food part. Here is one of mine...

[greyfox]

Mr. Harsey,

I'd be more than willing to share some academic presentations on the topic of Bulk Metallic Glasses. From my brief knowledge on the topic, it seems that the applications of the amorphous metal alloys such as Vitreloy, will be something that is going to explode in the next decade.

[Bill Harsey]

greyfox,
Are you talking about stuff like Liquidmetal?

[greyfox]

Mr. Harsey,

After a quick google search, it seems that one of the leading commercial companies of BMG's is in fact Liquid Metal; so in short, yes. In class we had only discussed the recent technological developments within the BMG field, not any of the manufacturers, so please forgive me if we've arrived at my original question in a somewhat round-about manner.

[Bill Harsey]

Mr. Harsey,

After a quick google search, it seems that one of the leading commercial companies of BMG's is in fact Liquid Metal; so in short, yes. In class we had only discussed the recent technological developments within the BMG field, not any of the manufacturers, so please forgive me if we've arrived at my original question in a somewhat round-about manner.

About six or seven years ago the Liquidmetal thing was announced to the knife world as the ultimate material from which to make knives, it was on the cover of our trade magazines etc. and has now fallen off the radar...in my circles anyway.

[Kit Carson]

Bill, I can help some on this subject.

I worked with Liquid Metal for awhile back in the 90s. Built several knives from it and wasn't impressed. The least bit of heat while grinding would make weak spots. It was difficult to put a decent finish on and you could never get that "sharp" edge when sharpening.

I still have a few pieces on hand, as a historical thing.

The maker that brought it forward isn't using it anymore. It can cause some medical problems that are hazardous.

http://www.liquidmetal.com/applications/dsp.sporting.asp

Also, do a Wiki search and read about Gallium and skin absorption.

If it's the future, I'm going back to school to learn plumbing or carpentry..

[x SF med]

Tactical Knives just did an article on Crucible's CPM-S35VN and noted that Chris Reeve had a hand (probably a whole arm and most of a leg or two) in it's formulation. From the write up the Niobium looks to have reduced the grain size, increased the uper limit for hardening, and really reduced chipping - tighter austensiting and martensiting is what appears to be the effect of the Niobium Carbides... Chris has already made a few knives from it, I'd love to get a chance to see how it sharpens and holds an edge.

Bill- any thoughts on Crucible's newest addition?

[Bill Harsey]

Kit,
Thanks for the help, info and warnings.

I've heard that the Liquidmetal is prone to micro fracture and then rapid fracture propagation and that is reason enough for me to stay well away from using it.

x SF med,
Your quite correct on all counts. I'm just starting to make some test blades out of the CPM S-35VN and am interested in seeing how it works. I think it's going to be good stuff.

[Bill Harsey]

Mr. Harsey,

After a quick google search, it seems that one of the leading commercial companies of BMG's is in fact Liquid Metal; so in short, yes. In class we had only discussed the recent technological developments within the BMG field, not any of the manufacturers, so please forgive me if we've arrived at my original question in a somewhat round-about manner.

Not dismissing this material. People have been working iron for about three thousand years to get it to this point so not ready to say Liquidmetal won't have knife applications.
Keep us posted, please.

[x SF med]

Bill, sounds like it's time for the Troll to visit "the Chapel of Our Lady of the Edged Weapons" again soon... if only to see you working the new steel. Colorado Low-Cal knifemaker fuel will be provided (and chocolate for Mrs. H).

[Aubrey]

I have read through this thread a couple of times as I have many of the threads in the Edged Weapons forum where I have been lurking for a while. I followed Mr. Harsey here from a link in his signature line on another forum IIRC. I have learned much here and know that my proper lane is one from which I should read much and post little. However, I'm curious about steels like H-1 that Spyderco is using for their maritime-application knives. It makes perfect sense that for such applications that one may need more than just "stainless" properties, i.e., real corrosion resistance. However, I've noticed that they are using H-1 on their incarnation of the Warrior and on a knife called the Jumpmaster.

My question to Bill, The Reaper, Sal, and other SMEs here is this: What are the pros and cons for using H-1 and similar alloys for general-purpose blades. What would one be giving up in exchange for "rust-proof"?

Many thanks in advance for your feedback and for being gentle with me as a first-time poster on this forum.

this from Spyderco's web page on the Aqua Salt:
"Whether sporting or laboring in saltwater two features rate highly in choosing a fixed blade utility knife, reliable cutting performance and the knife’s ability to remain rust free without maintenance. The knife industry toyed unsuccessfully with non-rusting steels for years until two years ago when Spyderco started manufacturing blades using an alloy called H-1. H1 is precipitation-hardened steel, utilizing .1% nitrogen instead of carbon. Carbon is the component in steel that makes the blade hard and allows it to hold an edge. Carbon also reacts to chloride, making rust. With nitrogen replacing the carbon; hardness and edge retention are realized but nitrogen doesn’t react to chloride so it physically cannot rust. "

[Ken Brock]

I'm not smart enough to know the steel science so I just take what the smart guys like Mr. Harsey say and run with it

[Les George]

I just got a sample of a "powder metallurgy" version of BG-42 from Carpenter... :cool:

[Ken Brock]

I just got a sample of a "powder metallurgy" version of BG-42 from Carpenter... :cool:


I hate you

[Les George]

:boohoo





why this time?

[Ken Brock]

:boohoo





why this time?


cause you got some cool new steel to work with

[Les George]

Want to make our collab out of it?



Just to keep in the materials topic. I have been working with the steel geeks at Carpenter Technologies for about a year now.

They do science and I try to break their stuff. It's pretty fun, me in community collage tell the PHDs what needs to happen! (I totally make 23% of my numbers up on the spot.)

Anyway, they have a great steel called CTS-XHP that I have really taken a liking too! Easy to work with, for the maker and the user, cuts great, resists stains.

As Mr Bill can attest too it's pretty tough, he tried to break my XHP test knife at Blade show, but ended up just breaking a table.

Now they are trying to refine other steels out there, thus the Powdered 42 that Ken is so jealous of.

I can post more info on the Carpenter steels if there is interest, or I can start a new thread about it, if that is better.

Let me know what you guys would like.

Thanks :munchin

[Bear043]

Yeah, I'd like to know more about it!!!

[x SF med]

cause you got some cool new steel to work with

Don't cry on the steel... we don't know exactly how stain resistant it is yet and the collaboration might have polka dots. :D

[Bill Harsey]

Want to make our collab out of it?



Just to keep in the materials topic. I have been working with the steel geeks at Carpenter Technologies for about a year now.

They do science and I try to break their stuff. It's pretty fun, me in community collage tell the PHDs what needs to happen! (I totally make 23% of my numbers up on the spot.)

Anyway, they have a great steel called CTS-XHP that I have really taken a liking too! Easy to work with, for the maker and the user, cuts great, resists stains.

As Mr Bill can attest too it's pretty tough, he tried to break my XHP test knife at Blade show, but ended up just breaking a table.

Now they are trying to refine other steels out there, thus the Powdered 42 that Ken is so jealous of.

I can post more info on the Carpenter steels if there is interest, or I can start a new thread about it, if that is better.

Let me know what you guys would like.

Thanks :munchin

Les,
Please keep us posted on the Carpenter Steels.

It might be best if you started a new thread for the Carpenter steels as this could get complicated all on it's own.

The BG-42 steel was what Bob Loveless used for his tough use knives. I would love to see the working results of that alloy in a particle metal steel.

oh yeah, they don't make tables like they used to. :D

[greyfox]

Mr. Harsey,

I was hoping you could divulge on the general heat treatment and sharpening process that you use in shop.

As I've read time and time again, the heat treatment process is seemingly just as important as the candidate material that you choose to work with. Through the little that I've learned concerning the process as a whole, its never been clear as to the chronological steps during heat treatment; I know that its standard to twice temper the material, as well as annealing and quenching, but in what order do these take place?

Secondly, I'm curious as to the sharpening parameters when producing a knife. I'm guessing that the strength of the metal, the size of the carbides, and the geometry play a roll in the final dimensions of the cutting edge, how is this determined?

[S.Gossman]

Tactical Knives just did an article on Crucible's CPM-S35VN and noted that Chris Reeve had a hand (probably a whole arm and most of a leg or two) in it's formulation. From the write up the Niobium looks to have reduced the grain size, increased the uper limit for hardening, and really reduced chipping - tighter austensiting and martensiting is what appears to be the effect of the Niobium Carbides... Chris has already made a few knives from it, I'd love to get a chance to see how it sharpens and holds an edge.

Bill- any thoughts on Crucible's newest addition?


SF med, I made a test knife out of this steel about 3 months ago and did some extensive testing for about a week. Cardboard slicing, over 1,000 slices, crossgrain batoning in wood knots, 100 push cuts in 5/8" diameter manila rope, also push cut through a 591 page Northern Tool catalog and other wood work such as whittling and batoning through seasoned oak. Never sharpened the knife and the edge was still very serviceable. After I was finished, I did resharpen.
Since then, I have been using as much as possible over the last three months. Just recently I gutted, skinned and butchered three whitetail deer using the knife. Even though it didn't need it, I did touch up the edge with my Schrade Honesteel. Edge holding and edge strength is exceptional.
Scott

[x SF med]

SF med, I made a test knife out of this steel about 3 months ago and did some extensive testing for about a week. Cardboard slicing, over 1,000 slices, crossgrain batoning in wood knots, 100 push cuts in 5/8" diameter manila rope, also push cut through a 591 page Northern Tool catalog and other wood work such as whittling and batoning through seasoned oak. Never sharpened the knife and the edge was still very serviceable. After I was finished, I did resharpen.
Since then, I have been using as much as possible over the last three months. Just recently I gutted, skinned and butchered three whitetail deer using the knife. Even though it didn't need it, I did touch up the edge with my Schrade Honesteel. Edge holding and edge strength is exceptional.
Scott


Scott.... Bill has asked me to try and break some of his designs... I'd be more than happy to try and break a knife for you also... :D

[S.Gossman]

Scott.... Bill has asked me to try and break some of his designs... I'd be more than happy to try and break a knife for you also... :D

LOL, I appreciate the offer. :D There are many of my blades in the hands of our military's finest warriors.
Scott

[Ironmike]

I have made good knives and threw away about as many as I have made. I mostly use the stock removal style. How ever I have hammered out a few.
The metal I have used most often is saw mill blades. Which is usally L-6 high carbon steel. I am making 2 now out of a kyser blade that the handle broke on. I have 10 or so blanks I have already ground out. I usally harden the knives in oil and then draw them back to temper. I like for the handles to be a little softer than the blades because the steel is so hard to drill. I am dyslexic
so please forgive my spelling.
I have made knives for people that drew out what they wanted. I also make hatchets out of t-500 boiler plate. My hatchets are very tough and do not bend or brake. I usally harden knives to 56 to 61 Rockwell hardness and hatchets to 54 to 58 . I do not sell knives but will trade for something else. If I buy my steel from the knife makers supply , I will charge for the steel's cost and I also put German silver on the handles. I do not care for stainless steel knives, they just will not sharpen like high carbon steel. But carbon steel will rust. I mirrow polish the blades. I have though about adonozing the blades but iI like them shiney . I do hope I have not trepased by making this reply. I am in my 60's and would love to pass along what I had to gleen very hard for. An old man named Skagel started making hand made knives and they were sent to G.I. during W.W.II he did not charge for them but they were highly prized by all who received them.
I do not buy or collect knives. I am a Fox Fire person and Fox Fire 1 is my favorite book. De Opresso Liber

[Roguish Lawyer]

CPM-S-30V versus CPM-S-35VN. Can someone compare and contrast? :munchin

[Barbarian]

The chemical composition of the two steels are slightly different.

CPM S-30V
Carbon: 1.45%
Chromium: 14%
Vanadium: 4%
Molybdenum: 2%

CPM S-35VN
Carbon: 1.45%
Chromium: 14%
Vanadium: 3%
Molybdenum: 2%
Niobium: 0.50%

The higher Vanadium content of S30V causes the steel to form more vanadium carbides, giving the steel higher wear resistance, but making the steel harder to work, and leaves little possibility for putting a mirror finish on a blade made of S30V.

The slightly lower Vanadium content of S35VN makes the steel easier to grind, drill, mill, and polish, and the addition of Niobium (formerly known as Columbian/Columbium) prevents sacrificing a significant measure of wear resistance, while making the steel more versatile.

So to boil it down, S35VN is easier to work, less prone to micro-chipping at higher hardness, and has only slightly less wear resistance than S30V. That's where my knowledge ends on the subject.

[DJ Urbanovsky]

The niobium in S35VN also helps give it a finer grain structure.

Bottom line on S35VN: Tougher and better wear resistance than S30V. And from my personal experiences, better corrosion resistance, despite having the same amount of chromium, and despite the data sheet claiming it is the same for both steels.

In my opinion, S35 is the steel that S30 should have been. It's crazy how just a little tweak in the chemistry can make such a big difference.

Here, data sheet for S35: http://www.crucible.com/PDFs%5CDataSheets2010%5CdsS35VNrev12010.pdf

[Night Stalker]

Sorry I did not read entire thread.

[Bill Harsey]

I found a few old hay cutters. I have started making a knife using files and a dremel. now I am trying to smooth out the rough stuff. Any tips on hardening it? I can sharpen it now to shave the hair of of me, but it is very soft metal. Thank you

Night Stalker, Have you read this entire thread?

[Night Stalker]

Night Stalker, Have you read this entire thread?

No I did not Bill I'm sorry. I have a lot of trouble concentrating and focus. I've asked the Team SGT to remove my account. The last thing I want to do is offend or upset anyone. All do respect to all of you.

[Bill Harsey]

No I did not Bill I'm sorry. I have a lot of trouble concentrating and focus. I've asked the Team SGT to remove my account. The last thing I want to do is offend or upset anyone. All do respect to all of you.

Night Stalker,
I wasn't asking you to leave, just hoping you'd read post no 11 (I think).

[Night Stalker]

Night Stalker, Have you read this entire thread?

Hey Thank you very much Bill that helped a lot. I was going to use brownells Templique.
On the other issue I think I have been jumping into threads where I should not be making a statement. I been having a pretty tuff time. My pain-attention span is shot.

[TCT_Knives]

I just finished reading all 180+ posts and nowhere on the internet will you find more applicable information compiled in one place! Awesome job Bill!

I'd like to chime in and talk briefly about the temper and how important it is. But first put into perspective the HRC # thrown around. Imagine a dial scale that reads 0 to 100. Similar to Celsius where 100 boils and 0 freezes, 100 on the Rockwell is equivalent to the hardness of a diamond, and 0 is just plain air.
As Bill has spoke about so eloquently, hard is not necessarily good. When a knife is quenched in either oil or air, it's at its hardest the chemical composition will allow. This is not a good thing because it's very brittle. Think of Ceramic or marble, they are very hard but hit them with a hammer and they will fracture. The same WILL happen to a blade, I've lost a few to loose fingers on the floor and I'm sure Bill has lost a few too. LOL
Thus comes the temper. If not done correctly you will be left with a brittle knife, or one that will bend on you and not flex back. The temper adds some ductility and adds "toughness". Unfortunately there are no scales that I know of that can read that. Therefore, you should ALWAYS use the manufactures recommendations on what temperature to use, for how long, and how many times. The Crucible website is a great source for this information.
Imagine a leaf spring or coil spring in a vehicle. It holds the weight of the car for it's entire life. It bends, contorts, springs and always goes back to it's original form. Has anyone tried to drill a leaf spring? How about the frame of the car? I challenge anyone to take a drill bit and give it a shot. Second thought, don't bother, you will just dull the bit. :) That is a direct result of car manufacturers figuring out how to heat treat a high carbon steel and temper it so it has that ductility.
Last word on Temper. Has anyone "Lost their temper"? That term was coined years ago by blacksmiths when a user of a dagger or knife he made came back with an issue. His first thought would be "Must of lost it's temper" or "Snapped". Thus when we get so mad and snap, we "lose out temper". A temper CAN be lost during the knifes life by a few bad practices. One being sharpening. If you are using any type of powered machine being a dry stone, belt, ect.. you can very easily create enough heat to pull the temper out and ruin that knife edge. Another mistake knife makers do is coat their knives with Duracoat, Ceracoat, or Powder coat not knowing how that "bake" will affect the temper. The above practices are legitimate and create either a nice ascetic appearance, or can prevent rust on a hi-carbon steel as long as you work that into your Temper. Don't take the knife to a higher temperature than it was tempered at or... you guessed it.
OK Bill, please make corrections LOL, you know I'm thick skinned.

[Team Sergeant]

I just finished reading all 180+ posts and nowhere on the internet will you find more applicable information compiled in one place! Awesome job Bill!

I'd like to chime in and talk briefly about the temper and how important it is. But first put into perspective the HRC # thrown around. Imagine a dial scale that reads 0 to 100. Similar to Celsius where 100 boils and 0 freezes, 100 on the Rockwell is equivalent to the hardness of a diamond, and 0 is just plain air.
As Bill has spoke about so eloquently, hard is not necessarily good. When a knife is quenched in either oil or air, it's at its hardest the chemical composition will allow. This is not a good thing because it's very brittle. Think of Ceramic or marble, they are very hard but hit them with a hammer and they will fracture. The same WILL happen to a blade, I've lost a few to loose fingers on the floor and I'm sure Bill has lost a few too. LOL
Thus comes the temper. If not done correctly you will be left with a brittle knife, or one that will bend on you and not flex back. The temper adds some ductility and adds "toughness". Unfortunately there are no scales that I know of that can read that. Therefore, you should ALWAYS use the manufactures recommendations on what temperature to use, for how long, and how many times. The Crucible website is a great source for this information.
Imagine a leaf spring or coil spring in a vehicle. It holds the weight of the car for it's entire life. It bends, contorts, springs and always goes back to it's original form. Has anyone tried to drill a leaf spring? How about the frame of the car? I challenge anyone to take a drill bit and give it a shot. Second thought, don't bother, you will just dull the bit. :) That is a direct result of car manufacturers figuring out how to heat treat a high carbon steel and temper it so it has that ductility.
Last word on Temper. Has anyone "Lost their temper"? That term was coined years ago by blacksmiths when a user of a dagger or knife he made came back with an issue. His first thought would be "Must of lost it's temper" or "Snapped". Thus when we get so mad and snap, we "lose out temper". A temper CAN be lost during the knifes life by a few bad practices. One being sharpening. If you are using any type of powered machine being a dry stone, belt, ect.. you can very easily create enough heat to pull the temper out and ruin that knife edge. Another mistake knife makers do is coat their knives with Duracoat, Ceracoat, or Powder coat not knowing how that "bake" will affect the temper. The above practices are legitimate and create either a nice ascetic appearance, or can prevent rust on a hi-carbon steel as long as you work that into your Temper. Don't take the knife to a higher temperature than it was tempered at or... you guessed it.
OK Bill, please make corrections LOL, you know I'm thick skinned.

Damn, you learn something new everyday! (Bill never told us that.....)

[Bill Harsey]

TCT_Knives,
Thank you. I never knew about the origin of "losing temper", I'd thought that was just something learned naturally while working in the woods logging.

[7624U]

So when the Smith takes the badly tempered blade from the owner and melts it down to make a new knife would that be considered a "Tantrum" ?

Then the owner then combines the two and has a "Temper Tantrum" thus acts like a child.

[pcfixer]

I'm still learning in the area of edged weapons.
Especially the steel they are made from.

I'm looking at a knife from Bark River.Bravo 1.5 s45v/Cru

:munchin:munchin