Tempering Question

[Greg Agresta]

I recently made a herb chopper using 1095 and quenched it after sharpening it. I forgot to temper it afterwards. My question is, is it too late? Can i do it now?  Also, how soon after quenching is best. My problem is my forge in not at my home so at best, I can't temper a blade for 1 or 2 later.  Thanks

[Dan Hertzson]

If it hasn't cracked or broken yet it isn't too late. 

 

As far as I know, for most steels, it is usually best to temper your blades as soon at they reach room temperature after the quench process to avoid potential cracking from the stress induced during  hardening.  Some folks temper in toaster ovens, though they aren't as consistent heaters as larger kitchen ovens.  Still you can often get them cheap, and I've found that if you bury your blade in a tray of sand for additional thermal mass, and calibrate the oven to be sure it is working as expected, they are adequate for a snap temper at least.  The controls on the newer electronic toaster ovens seem to be even better than the older dial units, but YMMV.  Why not pick one up for your shop?

[Greg Agresta]

I guess I should have asked, what happens to the choppers that weren't tempered soon enough. If you quench and then do nothing, what then??

 

[Joël Mercier]

It may crack or even break into pieces, or do nothing at all. But one thing is certain, the steel is in a very brittle state.

[Alex Middleton]

If you're asking about not tempering period, your edge will most likely be too brittle to last very long while you're using it.  It'll chip out ad require constant sharpening.  If you're just asking about a delay before you temper, the risk you run is, like Dan said, your blade cracking or breaking unexpectedly from built up stress.  I use a toaster oven with a hard fire brick in the bottom for doing my tempering.  I put an oven thermometer inside where I can see it instead of trying to use the dial so I can see a relatively accurate temperature reading.  At the very least, I would probably recommend a very quick, low heat (250-300 degrees) with a torch immediately after quenching if it's going to be a little while before you can temper.  That should help mitigate the risk.

[Will Wilcox]

On top of running the risk of breaking it, it's also going to be unnecessarily hard to sharpen. But it should stay sharp for a while! If it doesnt chip or otherwise break first.