Diferential Hardness--Which Steels?

[bruce]

I seem to remember that some types of steels are not compatible with differential hardness across a blade. If I remember right, the stainless steels fall in this category. If this is incorrect, could someone set me straight. If this is correct, what is it about these alloy steels that prohibit differential hardness (I realize you can get differential hardness by annealing the spine of an already hard blade or by only hardening the cutting edge of a soft blade). If chrome is the problem, how much chrome causes the problem? Where along the continium of chrome content do we lose the ability for differential hardness (01, A2, d2, ATS-34, 440-C, etc.)?

 

[Walt Welch]

Bruce; your question is not simply answered, as the Cr content itself doesn't correspond with hardening qualities. Go here and read this excellent description of various stainless steels. Walt

http://www.ssina.com/student.html

 

[tom mayo]

back in the dark ages gil hibben used to forge 440c.....but the exotic steels are best treated in an oven.....they are super tough...even at high rockwell...especially ats and 154cm ...i have a print out from a cal knives meeting where it took two heavy weights...over 250 lbs each...to break only one inch off a big bear type knife in 154.. the knife was in a vise and have been ground too thin and warped so it was sacrificed to the vise....they pushed as hard as they could before it finally snapped...point being,the tender body of one person would not be able to break a knife of this sort...

 

[bruce]

OK, Walt, I read the site and am smarter about stainless steel, but since my question wasn't addressed there, I would like to ask it in a more simple form. Can the stainless steels be differentially hardened? Mad Dog does this with 01 but are there makers out there who can differentially harden ATS-34, 440-C, CPM440V, D2, etc.? If not, why not? Just looking to expand my limited knowledge base.

 

[gregj62]

In theroy you can do it. I don't know anybody that does. With air hardening steels it makes it hard to do. Plus most knife maker that use ATS-34 and 440c and the others are stock removal guys, and most of those guys don't even do there own heat treat. They send them out and the people that do the heat treat can't thake the time to do a time comsuming job. So if anybody does a differential heat treat on those metals I bet it will be a blacksmith not a stock removal guy.

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-Greg Johnson
ICQ#4236341

 

[amacks]

Ah, check out Sean Perkins, his ats-34 knives are differentially heat treated, 60 at the edge, 55-52 throughout the rest of the blade and 45 at the haft
Aaron
http://www.perkinsknives.com

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Why did you stab that girl?
You won't believe this, but I had too much coffee!
-Edmond by David Mamet
aaronm@cs.brandeis.edu