Metalman
Years ago I case hardened a plain low carbon steel knife blade blank and then tried to further harden it with some cold hammering and that didn't work worth a darn - it cracked.  But I just read where some guy said that he was case hardening cheap stainless knife blades by just cold working by cold hammering.  I can see where this may have merit - I haven't tried it but I will when I have a chance.  I don't know, is this a common practice?  It sounds easier and less costly than dealing with 440C.   I assume he was hitting it with many lighter blows.  I am just not trying to sell knifes for a business - never sold one in my life.  Most everything that I have made I have given to son and grand kids...and none of it has been with any expensive metal.  At one time I was using old one inch wide power hacksaw blades and they didn't use them enough to dull them one bit.   
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Skarzs the Cave Troll
Hardening in that way has to do with the compression/refining of the molecules. I've never done it, but it's probably lots of small light blows.
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