Annealing straight razor

R

ricaga

Joined
Nov 3, 2021
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15
I thought I would try making a few wood carving knives from Straight razors. I had no idea how hard and I presume brittle the steel is. One is made from tungsteel which I might use as the blade is in remarkablely good shape. I don't have any trizact belts yet but I might have to bite the bullet. I spent 30 min on my 1x30 to do one profile and the spine? is still over 1/8 in thick. Is it possible to anneal and reharden at home. I'm using 36 grit belts and it's slow going
THX
 
You'll probably get better answers if you post this in the "Shop Talk - Bladesmith Questions and Answers" sub-forum.
 
Put it in a vice, get a torch to it, get it red hot (non-magnetic if you have a magnet around) and let it cool in air enough to handle. Should be softer then. If I'm understanding it right that's not annealing, but normalizing; effectively the same for what you're looking for (making it easier to work).

Would need to be rehardened before using it as a knife.
 
You can so this, but you're results are going to be hit or miss. Even using a forge it's not very exact, much less a torch, or a charcoal pit with forced air.

I would give more exact directions, but after looking up tungsteel, i have no clue how to advise on a proper heat treatment for it. A simple carbon steel would be somewhat doable, and would involve heating to above non magnetic, and sticking it in a medium for slow cooling like vermiculite. I've been thinking play sand may be able to work similarly. I've seen it used by people after welding cast iron. Provided it's completely dry.

Some advice i can give for sure. Is don't buy trizact belts for this they're going to do just as bad if not worse. Those are for finishing. Buy some ceramic belts. Norton blaze, or 3m cubitron. Blaze has 24 and 36 grit. They should do the job. I know they can grind hardned 10v, maxamet, and k390 no problem. So they should work well on this stuff.
 
One caveat for the above slow cooling advice: if you're going to use sand or vermiculite to slow cool an item without much mass, it is very important to preheat the sand or vermiculite first! Otherwise it will pull the heat right out of the item being slow cooled very rapidly. The slower you cool the steel, the softer and easier to work it will be. This doesn't make much difference when the item has a large mass because it will cool pretty slowly even in air, as the surface area to shed heat is small in relation to the volume of hot steel. When the surface area is large compared to the volume, (very small items or very thin cross sections - worse, both!) the item will cool very rapidly unless precautions are taken to avoid that happening.

Edit: I also posted here before I saw that this was a duplicate thread:

 
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Straight razors are super thin behind the edge usually, but like 3/16"-1/4" at the spine. If you anneal it, you will need to re heat treat the steel and quench. Unless it's a full or half wedge, it will probably warp like crazy or crack if you try to quench it to reharden it after annealing. You are better off working them cold and tempering them back a bit if they show to be too brittle for your use. It depends on the grind of your razor, but I think they would be too thin to make into woodworking tools unless its a wedge of some sort and not hollow ground much.
 
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