time between quench and temper

MarkJeffrey

MarkJeffrey

Joined
Nov 7, 2013
Messages
262
Is there anything wrong with tempering a blade, the day after (or longer) after you've quenched it? I feel like it's a silly question,. but I don't know the answer so... there ya go! I searched through some heat treating threads and didn't see this come up.
 
I don't know a lot about metallurgy but I BELIEVE that if you waited to long the temper would not work as well. I don't if that's true or really anything about it. I had a maker I spent a day with heat treat a couple of my blades but he didn't have enough time to temper them for me. He said that I HAD to temper them once I got home. So you definitely don't want to wait long...I just don't know all the specifics behind it.
 
Waiting is wrong.

In some steels it won't hurt much, in others it will stabilize RA and steel will be simply worse. And quick temper wont hurt any.
 
I didn't realize there was anything wrong with waiting overnight to temper a blade....regardless of RA. The only cavaet to that would be the built up stress. I've heard of knives surviving a quench, laid on the table to be tempered the next day, only to find that overnight it cracked on it's own. I understand that you want the steel to be close to room temp, or able to be handled with bare hands, before temper. Don't put it in there until it has cooled down to room temp or thereabouts.
 
Always temper immediately.
You want to relieve the stresses in the steel from the quench as soon as possible.
 
Those stresses of quenching can be very high !! If you don't relieve them quickly by tempering they might relieve themselves by CRACKING !!
 
Temper should follow quench as soon as practical.

That does not mean to rush and toss the still dripping blade in the temper oven, but it should be done shortly. I wash off the blades, dry them, and set in the already heated kitchen oven most times. When doing stainless, I have the HT oven drop to the temper while the blades are in the Dry ice bath.

Done within a half hour I would not worry. Longer delays will tend to stabilize RA and can cause spontaneous cracking. I have heard a W2 blade go "PING" while sitting on the anvil when I was forging and quenching a large batch of blades. 1095 and W2 are the most susceptible to cracking. They should get into a tempering oven as soon as possible. High alloy steels are most susceptible to RA.
 
I never thought it was a big deal to wait a few hours for my kiln to drop back down to tempering heat... until I heard a "tink" come from a thin 1095 kitchen knife after just over an hour. I didn't see any cracks but was convinced/curious enough to give it a 500F temper, followed by a flex test. Sure enough it snapped pretty effortlessly and the crack showed oxide colors almost half the width of the blade.

I now give them a snap temper in my house oven at 350F for 1hr.
 
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I use a cheap toaster oven set at 300 to at least releive some of the stress until my HT oven cools enough to do a proper temper. Keep in mind that the 300 degree in a toaster may range from 275 to 325 or so as the elements kick on and off. Not optimum but much better than leaving it laying on the bench.
 
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