Heat treating very thin 1084 or 1095?

Fitzhugh

Fitzhugh

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Feb 5, 2013
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What do I need to consider in addition to the usual when heat treating small, thin parts? I want to try making some small carving knives and very thin woodworking marking knives. I've got some of the thinnest 1084 Aldo sells but it it still about twice as thick as I want for the thinnest blades (it is 1/8th"). I'll try forging and grinding and see which I manage to do best. I have the feeling that heat treating might be tricky since the metal has so little thermal mass, if that is the right term - that it will change temperature much faster to match the environment (in forge, in quench, in air moving between forge and quench). I also am concerned about losing carbon on the surface since it is thin already and I've read a number of comments about the outer layer decarbing. I've got some clay I used to HT an odd, rasp-like blade a while ago - can't recall the name but it was suggested here). Would that help?

I also have a fair amount of 1095 that is only .025 or so, sold as rc 48 to rc 58 (card scrapers cut from scraps by a saw manufacturer). That is perfect for a few of the blades. Is that so thin I'll have problems? Anything I should try?

Thank you for any pointers, including of course suggestions to go read up - just please give me a hint what to look for.
 
My first guess would be to harden it thick and grind to the thinness you want.
Or possibly clay up the work like in file making. Maybe one of the more experienced makers could comment on that.
 
Thank you both. I'll read over the linked thread tonight.

I've long wanted to try hand stitching rasps and files so if you know of any sources please post them. I have not had luck finding detailed information. Or should be covered in some old text on Google books, archive.org or Gutenberg project somewhere. I did find info on the shape of the punch, how it is like a kernel of wheat (the French name for it is something like the name for a type of wheat or the kernel itself, or something. Uh, I guess it's late.)
Time to crash and take this up again tomorrow. I'll try a little series of test pieces tomorrow, or in a few days if my week is like I suspect it will.
 
The only area you might have a problem is going from heating to quenching quickly enough. Otherwise heat treat as standard 1084.
 
Just be prepared to expect warp. It happens in thin metal...but is also easy to straighten right out of the oil after about 8 seconds. Use gloves and work fast. If the blade gets stiff STOP straightening and do any further straightening during or after the second temper, and at 400F.

The time from oven/forge/torch/etc. to quench tank isn't as much of a rush as most folks worry about. Just do it in a smooth and safe movement. Rehearse it a few times with everything cold until you have it down...then get things hot.

.025" is a bit thin for anything but scalpel blades.
 
I would suggest that if you intend to make a few more card scrapers and thin blades, to invest in a couple aluminum plates to clamp them between right out of the quench. Stacy, tipped me off to this idea a few years ago for keeping knives/swords straight. It really works well. I have a vice set up with two 24" aluminum angle plates. I keep the vice "sloppy" to allow it to conform to distal tapers and such.
 
Have you tried aldo's 15n20?? ive made a few small knives from it in .093 ( it is available thinner) without any warping issues. seems to work very well at a high hardness. just my .02
 
Good suggestion. 15N20 has much more time to work and straighten, and it does not warp as much as the faster hardening steels.
 
I am following your responses with interest, just got pulled away from everything I want to pay attention to (like this) by other things.

I've looked up 15N20 and it looks like heat treating it would be challenging for me due to what I gather is a significant soak time - 10-15 minutes or something. I've just got a 2BF. I'm only making a few small knives for marking very tight dovetails - so really about the same as a scalpel. I'd just buy some scalpel blades but that lacks both learning and fun.

I'll try straightening any warp after quenching, unless I stumble on some aluminum plates - does it have to be aluminum if I'm using it just to prevent warp after oil quenching, or partial oil quench? Can it just be whatever metal plates I can find? I found this (adding it more so I'll know where to find it): http://www.bladeforums.com/forums/showthread.php/1061237-15N20-plate-quenching-question. Does 1084 in thin sections need short quench times as well?

The nice thing is I can mess up a handful and not cry. I have enough of the pieces to keep trying and it was included free by someone for a delay in an order. I would like to make a number of small carving knives and other very small blades so I'll probably return to try the stuff suggested here in the future.

In the mean time I've been making a much thicker marking knife out of the 3/16 1084. At least it will be easy to sharpen. The oven is heating now so I can tempering it after quenching it.

Thanks
 
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