Delayed tempering?

T

Tomaz L.

Joined
Jan 20, 2005
Messages
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I understand blades should generally be tempered very quickly after quenching. However, what happens if there is a delay of say, several hours between the quenching a blade and putting it in the tempering oven?
 
You need to get the austenite transformed and the martensite tempered. Temper immediately upon cooling to the appropriate temperature and there after further tempering is less critical in amount of time between. , i.e. you can wait until tomorrow to further temper.

RL
 
Quenching stresses can be very high and if you don't relieve those stresses by tempering immediately they may relieve themselves by cracking the blade.
 
If the blade hasn't cracked, then the delay is fine, but it's generally not a risk you want to take. What I like to do is do a snap temper at around 325F just to relieve the stress, then worry about getting the proper hardness with a real temper later.
 
I normaly temper imeadatly with most steels except 52100. Only had one blade to crack so far that might have been linked to waiting, but then again it might not have been the cause. Normally with 52100 I quench three times 24 hours apart, letting the blade cool down in the oil to room temp then to the freezer till the next day. I wait 24 hours after the last to start tempering. Only had one blade crack so far and I'm not sure but believe that was due to fullering the tange at to low a temp.
 
A 'snap temper' is used to relieve the quenching stresses if the normal tempering is delayed or as a precaution if you are doing cryo. It is 300-350F.If you are doing cryo to remove retained austenite a snap temper of 400F will stabilize the austenite so you won't convert all the austenite.
 
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