steel university?

hardheart said:
This one is interesting, makes me wonder why they do a cryo treatment for the 52100 in the Swamp Rat knives.
Click to expand...

You don't perform cryogenics for austenite conversion, that is why you use cold treatments. Cryogenics, or deep cold, is don't to effect the crystal structure in several ways, mainly to augment the wear resistance. There have been some claims about toughness but I have as of yet seen no published papers to support that proposition.

However regarding austenite, it generally is not a good idea to leave a blade full of austensite to increase the toughness as the austenite at the edge creates weak points. The austensite will also transform to martensite over time anyway, especially when it is stressed and now you have a blade with untempered martensite.

Once you use cold treatments to fully transform the blade to martensite you then temper accordingly to produce the martensite with the required strength/toughness. Since there is a higher percentage of martensite this means you can temper it hotter, and thus the martensite will be significantly tougher than the martensite in the martensite/austenite blade of the same hardness.

You can also just ask Busse directly why they use Cryogenics. He doesn't tend to avoid direct questions.

-Cliff
 
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