Snap temper

[MikeS]

Good morning to everyone. I need a little help please. I have been looking for old thread to study and to say the least I have not found it. My question is simple. How to do a “snap temper”.i have a run of 15-20 hunters and I want to snap temper them so that my regular heat treating oven can cool down. My steel is 1084 3/16 in the spine . My blades will rough ground and then heat treated, snap temper, final temper and then finish ground, sanded etc to finish.
Any suggestions or help is a real help.
Thanks ahead of time
Mike

 

[opaul]

Can you put them in a bucket of clay cat litter or perlite ?
Is it just a step before actual tempering.

 

[KenH]

Mike, I've been waiting for somebody else to chime in with more knowledge than I have. I did find the following by Kevin Cashen on

Snap Temper Question

l don't have a tempering oven apart from my evenheat. If I snap temper at 350F while waiting on the evenheat to cool down, do I have to leave it in th...

www.americanbladesmith.org

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Below 300F in simple carbon systems all that is happening is the relaxation of the body centered tetragonal nature of the hardened steel, so this is essentially just relaxing the strain of hardening. If a quenchant with good cooling curves is used there will be much less of added strain above and beyond what is necessary, so the will be less urgency. If the quenchant is too fast for the depth of hardening there will be added strain above what is needed for maximum hardness and the quicker you can relieve it the better. The first phase of tempering (as defined by temperature) will just be this relaxation, above 350F and the precipitation phases will begin and you will start to change the structures present. It is the accumulation of secondary carbides that results in the destabilization and possible conversion of retained austenite, this is why steels that could benefit from cold treatments are best snap tempered below these ranges, it allows for a "purer" martensitic conversion, which must then also be tempered again.
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I think what he's saying is a good snap temper can be <300°F and relax the metal so it doesn't crack while waiting for the real temper. Maybe somebody more knowledgeable will chime in with comments.

 

[Edwardshandmadeknives]

I preheat the oven in my kitchen to 300° and put them in there. Check your actual oven temperature though before you do that. They can vary a lot. I have to set mine to 290 to get 300. You don’t want to overshoot it and accidentally snap temper them hotter than your actual temper will be.