Tempering after the fact

[beardedblades]

Hello,

I am very new to knife making I have a question about tempering I couldn't find the answer anywhere. I am wondering if I harden a knife and something comes up and i have to leave a knife after hardening and forget about it for a week or two can i temper it at that time or do i have to normalized it and re harden and temper in a short period of time?

Any advice / input would be greatly appreciated.

 

[Taximanny]

I believe you would have to state what kind of steel you are using.
Than I think people could answer.

 

[S.Alexander]

In certain steels, a knife will crack if not tempered within a reasonable amount of time.

 

[JTknives]

I would try and temper as soo as you can. I had a blade crack in my hand once while I was waiting for the oven to heat up. So now I get the oven ready to go and go stright to it right after the quench.

 

[stezann]

If you find your blade still intact you can temper anytime, it could be years later.
But the guys said an important truth, untempered steel is under huge strain, so could eventually crack anytime before tempering...better planning the whole heat treatment when you know you have enough time to do it properly.

 

[Stacy E. Apelt - Bladesmith]

In simple carbon steels the risk is that it may crack under the great internal stress. If dropped, it may shatter. Otherwise, a delay in temper will not cause any harm.

With stainless and high alloy steels, the major risk is that the RA will become stabilized ( also some internal carbide structures may end up different). This may make it not retain the edge as long. Stainless steel should be tempered as soon after the quench as possible. The longer the delay, the more stabilized the RA becomes.


If you can't do a full set of tempers, a "snap" temper is a good idea. It is a 20-30 minute temper at around 300°F. This will be enough to release stress. The actual temper cycles should be done as soon as possible for the best metallurgical results. However, waiting a day is OK if you have to.

 

[beardedblades]

Thank you all for the input I have a blade that had to be left and still intact I understand that it may not be ideal but I will temper it and use as is if for nothing else then a science experiment to see what differences there are. Thanks again for the input and I'm sure to read a many other threads and ask more questions as I am quite enjoying making knives.