Thread: How to heat treat a file?

I got a great big file this week I want to use to make a razor out of. But of course the file is still hardened. Who can help me with what temperatures I need to get it soft enough to work with and for how long it would need to be at that temp?

And after softening and working the metal, what would the best temps be to harden again and what process? Oil cooling, air, water etc?

I can use a professional grade heating oven to heat so it's down to the degree and minute precise if needed.

Who could help me with some hard needed advise

Thanks.

Without knowing the exact steel it's made out of its hard to say what exact temp is needed. But as a basic, heat the file up so its a nice glowing orange (or about 1500 if using the oven) for a few minutes then let it cool slowly (annealing) this will make it soft enough to work, and if it still seems very hard, repeat.

As far as heat treating your probably looking at around 1450-1500 deg F for about 5 min then quench in oil would be my suggestion. And then around a 2 hour temper at 450, that should get you in the ball park of 59-61 HRC assuming its W2 or something of the like.

An old file would likely be a simple carbon steel. New files could be anything that has been case hardened only deep enough to have hard teeth then get thrown away (disposable economy and cheap!)

To anneal such a piece, heat to the 1500 F (800C) for five minutes then put into a bucket of ashes that cover the whole blade and let it cool down slowly overnight. Any insulator, like vermiculite, or similar will work as long as it doesn't burn. Then it should be soft enough to grind easier. Heat treatment is as mentioned above. If the blade hardens at all it's good steel. If it's the disposable kind of new manufacture, it won't harden at all.

Good luck.

If you dont have vermiculite or simiar, you can heat it to temp in the oven and then turn the oven off and let it cool in there. It may not be fully soft but more than workable if it is a simple carbon steel. To anneal stainless you can program the cooling of the oven, like 25 degree's per hour(specifics depend on the steel type) to correctly cool the steel. Having a ht oven greatly increases your chance for success.

For annealing I put a thick, flattened iron pipe in the fire, with one end closed off, and put my knives in the pipe.
I heat it until both the pipe and the knives are glowing orange, and stop the air flow feeding the fire.
the fire will die down gradually and the thermal inertia of the pipe will make sure it cools down really really slowly.
After that they are annealled.

i've had no trouble working files simply heated red and left to air cool for annealing.

of course, once shaped i heat them again, harden via quench, polish bright (to read your color) and draw back with controlled heat. ancient steel-working traditions. Just basics, but i'm making tools, not razors here.

Thanks for the input guys. Great info, helps a lot

Originally Posted by WadePatton

i've had no trouble working files simply heated red and left to air cool for annealing.

of course, once shaped i heat them again, harden via quench, polish bright (to read your color) and draw back with controlled heat. ancient steel-working traditions. Just basics, but i'm making tools, not razors here.

For knives you want to anneal before quenching. It reduces the amount of warp you will get, as well as reduce grain size.

Originally Posted by Bruno

For knives you want to anneal before quenching. It reduces the amount of warp you will get, as well as reduce grain size.

I found out that one the hard way...

Originally Posted by shooter74743

I found out that one the hard way...

Make a long thin knife from O1, and then quench in icecold water
Did that once, just for laughs