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So I know steel can be work hardened by stressing it to yield stress slowly, then unloading it slowly. Would this have any benefit on razors do you think? I feel like it would allow a small increase in edge holding but i want to know your opinions. Thanks!
work hardening was the method for sharpening bronze and iron tools way back in my younger days. We sorta gave up on it once steel heat treating methods were developed.
Since the razor blade is already Ht'd and rather hard, the only method I know to be effective-careful hammering on anvil- would not be advised.
How were you planning to proceed?
I think Keven is right. The blades are quite brittle. The hardening and tempering is understood and probably done properly on a quality blade.
Way back in the last century when I was an ironworker apprentice I had a book put out by the Lincoln welding supply co called Metals and How To Weld Them. In it were some basics on metallurgy pertinent to welding.
It mentioned Manganese steel as being an alloy that became harder under impact so that the teeth on dragline buckets, treads on movable heavy cranes on track and things like that would be made with Manganese. Sifting plates on Klinker coolers were made with stainless because of the abrasion resistance of the stuff. I think of that when I am honing some of mine. :)
I've always been fascinated that razors were made from the stuff and have a few. Work hardening from our point of view, ironworkers that is, has a negative connotation. It eventually leads to the object or member failing and that is never a good thing. I don't know if it would apply to razors at all, at least not in the way that I understand it. Maybe cold working but not work hardening ...IMO.
Jimmy, I think you are correct about those types of steel when used in forming dies etc. They are not hardened to the same degree for that use. Razors are hardened to the point of being brittle.
The amount of manganese necessary for increasing the hardenability of steel is between 0.9-1.2%, or more, by weight. Not very much really. But for work hardening steels like railroad rail or the others mentioned, it can be as high as 12% or so. Manganese and iron are often found in very close proximity in the ore mines.
Interestingly, the steel analysis project from Josh seemed to indicate very low manganese steels. IMO that is a desirable state as is reduces the chances of the blades being brittle to some degree. The minor alloying elements have very large effects on the outcome. The maker has to account for those in the heat treatment equation.
I sent an old Cattaraugus to Josh to contribute to the steel analysis project. I was unaware that he had ever pursued the project to the extent of having any testing done or conclusions on the various samples contributed ?Quote:
Originally Posted by Mike Blue
I guess Josh has found other fish to fry or is extremely busy. Too busy to post on the forum. I have a couple of his hand forged razors and I'm glad that I do. They are real nice shavers. I miss his posts, they were always thoughtful and informative.
I miss his contributions as well. All I ever had from Josh was the most preliminary blush of information about some of the razors tested. I don't know if any conclusions resulted. One of the pieces I can safely state I remember the best, was that despite the diversity of makers, spread over several important razor-making regions, the steel was remarkably consistent, nearly homogenous. But, as with all sorts of research, threats to validity, in this case, a small sample size may mean a wrong conclusion.Quote:
Originally Posted by JimmyHAD
Hammering accomplishes compressive stress, I was thinking of taking say, 1" by 7" by whatever thickness stock and "stretching" it gradually. Like in tensile testing. Here's a graph- the unloading/reloading curve demonstrates that one can extend the yield stress closer to the ultimate stress through work hardening...
Do you mean something along this line? DiamondBlade Knives
I can't quite gather what is going on there, but I'm really tired right now, so...
Kaos are you talking about hammer forging a blade like they do some rifle barrels? My CZ's are hammer forged.
It can be compressive or tensile stress, doesn't matter. So yes, hammer forging counts. (what are CZ's btw?)
I was also talking about loading stock with tensile force prior to stock removal techniques though.
CZ-USA -> CZ 527 VARMINT The barrel starts out as a short billit and is hammered around a mandrill. The outside shape is formed and the barrel is rifled by the mandrill. I think the machine costs around $1/2 million
Honestly it sounds like overkill. Modern heat treat techniques (normalizing, etc.) pretty much relieve any stress that you need to in a straight razor. It's kind of like using a power hammer to peen a razor. It's just unnecessary and too complicated to validate the outcome (my opinion and all that).
Okay now I know where you're going. I agree with Philadelph. For the section thickness at the end of all that processing, the thermal cycling in preparation for heat treatment and the final hardening and tempering will reset to zero any gains made by attempts to work harden the material.
The choice is to work harden the material and risk it coming apart during the forging/peening, or to use the regular methods of heat treatment to achieve hardening. I haver the feeling that you would fracture your piece long before coming close to a razor thickness.
But, if you consistently anneal the material, and choose the right material in the first place, during the forging, you could theoretically do it. Each time you anneal the material you eliminate any hardness gained by forging. It would be an exercise in proof of concept and not very practical given the ease of doing things "normally."