Re-Heat Treat to Straighten Blade?

I want to preface this question by saying that besides the basic concept of heat treating blades I don't know too much about it. I send all my blades off for heat treat.

I have some blades that were heat treated 5 or 6 years ago that I've finally got interested in finishing and I noticed that one of them has a fairly decent warp in the tip. Until recently this warp has remained hidden under a thick layer of dried peanut oil.

Is it possible to send this blade back out for re-heat treat with the possibility of straightening or is it a loss? The blade is 3/16" O1.

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Short answer is yes.....first needs to be annealed, then straightened, then re-hardened and tempered......

You can easily anneal then straighten yourself with a torch....then send out for heat treatment....

That sounds easy enough. I actually have a pottery kiln that will take the steel to non-magnetic. I simply heat and then let cool? Does this need to be done more than once and is there a particular "soak" time at non-magnetic?

Thanks for the help!


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You should be able to google annealing that steel....

If you can program your kiln.

Ramp to 1500 ... 10 min Hold

Cool to 1450 ... 10 min hold

Cool to 1400 ... 10 min hold

Cool to 1350 ... 10 min hold

Cool to 1300 ... 10 min hold

Cool to 1250 ... 10 min hold

Cool to 1200 ... 10 min hold

Let cool in to room temp over night in oven

If you can't program your kiln; anneal it in vermiculite or ash. Get the blade to temp and let soak in vermiculite or ash 24 hours. It's also good to preheat vermiculite or ash buy inserting a buddy steel along with it. If I'm only doing one piece of steel I place another piece of steel in the material that is around 1500 degrees or more, so that when you put the piece you want to anneal doesn't cool too fast.

Others might have a better way but this works for me. I do this after forging and normalizing then I anneal.

I just put the hardened steel in my oven and take it up to 1500° then turn the oven off and let it cool in the oven overnight. I never open the door on the oven until the next morning letting it cool very slowly. Steel is soft enough to work by then.

Thanks Mike; I've never done that. I have to anneal is when I'm finished with the forging process and I always have a five gallon bucket with vermiculite, been doing that a long time. When I first started making knives ( long ago ) and didn't have the right equipment I used files and rasps and tried heating them in fire and left them over night to cool, all I got was a lot of warped steel. Then I discovered ash or vermiculite and been doing that ever since, works for me.

Temper the blade while clamped flat or curved the opposite of the at rest Bend. No need to start over (probably).

Just to add, what I'm referring to is carbon steel. I've never tried it with stainless but I've never had a stainless blade warp either.

Awesome, thanks for the advice! I'll give the re-tempering a shot. If that doesn't work, I'll anneal it and send it back out.