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Old 05-08-2006, 19:23   #51
Bill Harsey
Bladesmith to the Quiet Professionals
 
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Join Date: Feb 2004
Location: Oregon, Land of the Silver Grey Sunsets
Posts: 3,886
CPTAUSRET,
After main work hours, here's more answer to your question about cryogenic treatment of tool steels.

The reason we deep freeze tool steels is to force retained austenite produced during the high temperature phase to convert to martensite.
This happens because the freezing increases the mechanical driving force in the steel to complete this transformation.
This must be done during the initial heat treat cycle or the steel tends to "set" and the freeze will have much less ability to do any good.

Retained austenite in the steel causes weakness and we don't like weakness around professionalsoldiers.com. Just ask the Team Sergeant.
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