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.
Hybrid Mode
