Tempering Question

Merle

Active Member
#1
Question for you guys.... What is the reason for doing tempering in separate shorter cycles, as opposed to a single longer cycle. For example many recommendations are something along the lines of "temper at TWICE at 400F for two hours each"

What would be the difference in just doing a single longer soak at the prescribed temperature (e.g. 4 hours at 400F)? Does cooling back to room temperature periodically achieve something in the steel?

thanks, andy
 
Last edited:

Doug Lester

Well-Known Member
#2
Actually it may not make any difference depending upon the alloy in question. Cooling may trigger retained austenite in some alloys to convert to untempered martinsite and a second tempering cycle will will temper it. Most of the change caused by tempering will occur in two hours so if I were to do two cycles I would do two one hour cycles. Three cycles would be overkill but they wouldn't hurt anything. Nor would accidently leaving the blade in the oven overnight.

Doug
 
#4
Nor would accidently leaving the blade in the oven overnight.
That sounds like something I might do. Man that would drive my wife crazy. I have a toaster oven With a seperate thermometer I do mine in because it has a 2 hour timer. So if I forget it will turn off without me. Safety first...trusting my memory...dead last.
 
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