Thread: Annealing steel

I got this from Mike Blue.
If you want to know for sure that a piece of steel is as soft as it can be, you have to anneal it before working on it. That way you can save yourself time and effort, since you cannot know how the steel was treated before it came to you.

You have to heat the steel till it is red hot and demagnetised completely. You can check this with a magnet.
At that point you immerse it in something that acts as a perfect insulator. Wood ash is a perfect material for this. Then leave it to cool off over at least 24 hours.

Be careful: wood ash is a perfect insulator. If you stick your hands in the ash after 24 hours, there is a real chance of burning your fingers really bad because the steel will still be hot enough to burn you.

Some practical points: you need a pair of tongs or vice grips so that you can remove the steel from the fire to check the temperature, and place it back if needed.

I was already firing the steel when I discovered this practical problem. Also, since I was abusing my smallish bbq for this, putting the big piece of steel back underneath the coals was a bit of a problem.
So I decided to simply stoke it as hot as possible, and then extinguish the flames by pouring a bucket of ash over the coals.

This was a partial sucess. Since I did not have a bandsaw, I simply used a hacksaw to cut off a strip of metal lengthwise for my first project (a Japanese style cutting knife for my mother).
As I was sawing I discovered that the part that had been in the core of the fire was noticably harder than that part outside of the core, which was also the part I could peek at through a hole between the coals.

Cutting all the way through took a lot of time and effort.
The nice thing about doing things by hand though (at least the first couple of times) is that it really teaches me a lot about the metal that I would never learn if I used power tools, because I simply wouldn't notice.

Bruno,

This new forum is fun. Tell me if you want me to shut up.

Before you try to anneal a piece of bar stock, it's worth trying to cut it or file it to gauge its hardness. If it cuts or files pretty well, then you might be better off just working it as is.

Some steels come from the mill in a super-soft condition, and once you heat them up you'll never get them that soft again without sophisticated equipment.

I recently forged a blade out of O1, and once it was ground I was unable to drill the hole in the tang. Forging takes the blade well above critical, and once it cools down again it hardens to some extent. I ruined several drill bits on it, and I've tried different annealing and softening treatments to no avail.

From now on, I'm going to use O1 for stock removal only. It grinds and drills like butter when it's new, but once I forge it it hardens up. Gah.

Josh

Originally Posted by JoshEarl

Bruno,

This new forum is fun. Tell me if you want me to shut up.

Before you try to anneal a piece of bar stock, it's worth trying to cut it or file it to gauge its hardness. If it cuts or files pretty well, then you might be better off just working it as is.

I don't.
I did.
And it didn't.


I don't shy away from anything atm, because anything I do can only increase my first hand knowledge about steel.
I filed before and after, and it is definitely softer than what I started with. At least the part that was in the core of the fire.

Here's a link to my ongoing discussion at bladeforums.com:
http://www.bladeforums.com/forums/sh...d.php?t=554489

Sounds like your steel was hardened to begin with, so annealing is a good call.

Josh

If I manage to forge harden my blade then I always anneal it again before drilling the pivot hole.

Either drill your pivot hole right after the anneal or after the second anneal.

My grinders are almost done!

As a youngster in the 50's I was lucky enough to know a Welsh blacksmith whom had gone through an apprenticeship as a youngster. He would heat the steel in the forge, then put it in a metal box full of lime and close the lid. He swore by lime, and said it wasn't the only material good for annealing metal, but one of the best.
Ken.

There are other options for insulators as well, you can get ceramic blanket on ebay, haven't tried it myself but it's supposed to work similarly.

The ceramic wool blanket works well, thats what I use inside an old metal tool box.

Great! I have had a 2'x1'x2" piece laying around for a while, maybe I'll give it a shot this weekend.

How much would be necessary to make it effective?

I use 1" thick blanket, about 2 layers thick so I think you have more than enough. Just be sure to have the ends closed up.