Edge quenching help?

[sfoo]

For the record, I've done 3 blades and about 6 cutting tools out of O1 that I've fully hardened by pure dumb luck it seems.

However, last night I was working on a blade I've been goofing with (it's really goofy, too). 1/8"x1x~9" long hunter-type with a funky handle. Pre warmed it in my mini-foundry. Then heated it to the point I could see shadows dancing, which is what I look for, cut the flames, grabbed it with my tongs, and went to do an edge quench of it (my first attempt). I'm using about a gallon of vegetable oil, since i got it cheap for quenchant, and had heated it beforehand. I held the edge in the oil for about thirty seconds, then dunked the blade fully into the oil. swished in a linear cutting motion under the oil, then withdrew, and inside to the toaster oven (wife's away ). Tempered at 400 for an hour, then let it sit overnight.

Two things happened that I haven't had happen before. One, the spine (but not the edge) and the last inch of the handle warped. Not very much, say 1/32, but still very noticable to me. Second, as I was testing the hardening/tempering, first with the file test (skated nicely off the edge, bit into the handle area). Then I applied moderate bending pressure with my hands to see if it would snap. It didn't. instead it made a nice 30 degree bend.

I think I'm missing something im my process and am looking to you all to enlighten me as to what it is.
A, how can I avoid the curvature?
B, for edge quenching is there a "better" way to do it?
C, anything else I should be thinking about when I try this?

Thanks,

An inexperienced wannabe.

 

[Jason Arnold]

Two things happened that I haven't had happen before. One, the spine (but not the edge) and the last inch of the handle curved.

Do you mean curved as in a curved profile? Like a moon as opposed to a ruler? Not a warped, no longer flat blade?

If you mean curved, that is due to the back shrinking and the edge remaining expanded with lots of hard martensite.

To avoid it you might try, waiting less before emerging the body/tang. Try putting the body in as soon as it loses color.

That's my .02. Experiment and try everybody's suggestions to find out what works best for you.

 

[sfoo]

Originally posted by Jason Arnold
Do you mean curved as in a curved profile? Like a moon as opposed to a ruler? Not a warped, no longer flat blade?

No, but that would have been neat.

This was warped. Sorry I will edit to make that clearer. The edge stayed straight, the spine warped.

 

[Jason Arnold]

Well, warping is not an uncommon problem, especially using the methods you have at your disposal. If its minor, it can be as simple at grinding it out. Best ways to avoid it are:

1. Make sure your heat(s) are as even as possible on the blade just before quenching.

2. When agitating in quench, try your best to keep it perfectly straight, do not sway the blade against the bevels, especially in the first few critical seconds. Use the stabbing/cutting motion.

3. Make sure your knife is as symetrical in grinding/or forged dimensions as possible prior to heating for a quench.

4. You might try heating the quench a little to make it less drastic, which can also be the cause of warping. Like 125-150°F. Don't worry veggie oil won't flash at those temps. 0-1 hardens rather easily and gives you a big "window" to get things right, so allow yourself that space and warm things up.

5. Still try emerging that blade as soon as the color goes out in the body.

6. Add another hour in that temper.

7. Welcome to the club.

 

[peter nap]

Jason pretty much covered all the bases except three...normalize, Normalize and NORMALIZE. You still may get a little warpage. There are so many things that can cause it and sometimes it just happens. It's a fact of life and is one of the reasons I don't grind beyond 85% before the Heat treat.