440-c

J

jrhartman

Guest
I have a ? on 440-c and cyro.
After i heat and quench is it best to cyro before i temper and for how long?
Thanks JRH.
 
Yes,go from oven to quench plates to room temp then into cryo for 4-6 hrs. and then temper.When coming out of cryo let them warm to room temp on thier own.
Stan
 
What's the rationale for 4-6 hours of cryo? I get the 2 points hardness increase from just dipping in and out.
 
From allI have read on cryo total transformation of RA takes 4 to six hrs.You may get the extra hardness by dipping in and out but not get the added toughness of converting all the RA.
Stan
 
Here's how I do it and have had great results:

1930'F x 20 minutes
Plate quench
1st Temper 400'F x 2 hours
Cryo in liquid nitrogen overnight
2nd Temper 400'F x 2 hours
3rd Temper 400'F x 2 hours

BC
 
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