Kevin R. Cashen
Super Moderator
Don’t get me wrong Fellhoelter, I am squarely in your corner here as I rely heavily on Rockwell hardness in my evaluation. But there are many who feel as long as they get a certain HRC number that they have all they need to know about the knife, and it is those folks I am trying to reach to let them know that only if you have all of your ducks a very tight, rigid, row can you rely on one test in such a way. I will take a good Rockwell number over just about any commonly used bladesmith “test” to evaluate blades, e.g. bending in a vice, flexing on brass rods, mincing rope for hours etc… which are all incredibly subjective and often don’t even measure the properties we are looking for. The Rockwell test on the other hand does very accurately measure penetrative hardness in ways no other test can, and produces very standardized and repeatable numbers.
But the numbers must be taken in context. I think the Rockwell tests works best for those who have a good handle on and control over the entire heat treating process, for then they can be more confident as to why they are getting the readings they are getting. If somebody is heat treating in a camp fire or with a torch and has no way whatsoever of gauging temperature, Rockwell will be of little more benefit than just whacking away at a hard object. For example, say you used a torch and overheat the steel, overheated steel actually hardens much more deeply so your HRC readings will tell you your heat treat is really great due the high hardness you are achieving, what it is not telling you is that you are getting that hardness because your grains are the size of golf balls. In this case Rockwell is misleading but a good chop, or even a flex over a metal rod, could reveal the serious flaw in that blade.
But if one has good control and consistency in their heat treatment, I entirely agree that accurate Rockwelll numbers are an invaluable tool, and one that I rely on every day. I know they are reliable because I verify them with other tests equally as reliable and scientifically accurate.
But the numbers must be taken in context. I think the Rockwell tests works best for those who have a good handle on and control over the entire heat treating process, for then they can be more confident as to why they are getting the readings they are getting. If somebody is heat treating in a camp fire or with a torch and has no way whatsoever of gauging temperature, Rockwell will be of little more benefit than just whacking away at a hard object. For example, say you used a torch and overheat the steel, overheated steel actually hardens much more deeply so your HRC readings will tell you your heat treat is really great due the high hardness you are achieving, what it is not telling you is that you are getting that hardness because your grains are the size of golf balls. In this case Rockwell is misleading but a good chop, or even a flex over a metal rod, could reveal the serious flaw in that blade.
But if one has good control and consistency in their heat treatment, I entirely agree that accurate Rockwelll numbers are an invaluable tool, and one that I rely on every day. I know they are reliable because I verify them with other tests equally as reliable and scientifically accurate.