Thread: Stainless Steel Hardness

I would like to thank you all for the helpful and valid answers. Once again, I learned many things in this place.

Originally Posted by Slur

It is difficult for me to believe that two different alloys have exactly that same hardness, and that the strength of the blade depends only on the heat treatment.
It is more likely that two different alloys have different hardness when both undergo the same heat treatment.

The heat treatment is where the real value of adding all the alloys occurs. The heat treatment must take into account all the elements in that particular steel to take full advantage of the potential. The best steel you can possibly find, may well have a very narrow range of optimum potential and will be useless if poorly heat treated. Likewise, some steels have a wide range of performance and can be poorly heat treated and still function well enough but not at their optimum potential.

A stainless example: 440C used to be a difficult steel to get to perform well. If it was hard, it sharpened nicely, but fractured very easily (i.e. not very tough), but cut back on the hardness and it was quite tough, but then gained a reputation for not holding an edge, or being difficult to sharpen because you could not develop an edge that would be durable. Fellows, such as Paul Bos, were very good at obtaining a balanced heat treatment using controlled atmospheres. Folks like that heat treating stainless steels can return some of the reputation that 400 series steels should not have lost. But, say 15-20 years ago, that knowledge was not available to the same degree it is today, and steels gained the reputation for being either hard or tough, you could not have both at the same time.

A carbon steel example: My best friend is Howard Clark. I watched him develop heat treatment regimens that can take an old unfashionable steel, L6, and turn it into a sharp hard and unbreakable blade. That has to do only with the potential in the steel and the correct, controlled heat treatment of the material. Similarly, I've found that an old fashioned underrated knife steel like O-1 has some of the same potential especially in razors, if the heat treatment is controlled correctly. There are several Chandler/Blue collaborations out there in someone's hands that will likely defy attempts to break them. Or, perhaps better said, they will not break when clacked against the sink or the faucet as other blades would. Not that I am suggesting that any owners take the chance, but there are a couple I've tried to break with a hammer before they went out to Joe to finish. I know they exist. I know what they are capable of because I took them well past what any reasonable purchaser would do. And, they survived my attempts to become completed blades. All because the secret lies in the heat treatment.