[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