Annealing D2

[Lo/Rez]

A guy from work gave me some planer blades that are made from D2. Can I anneal these with a torch or should I wait till I get an oven before I work with them?

 

[Stacy E. Apelt - Bladesmith]

No, you need a programmable HT oven.

 

[Lo/Rez]

Thanks for the reply. I think I may not have expressed myself properly (maybe used the wrong term?). Can I take the hardness out of these so they are easier to grind and then go through the heat treatment process when I get my oven?

 

[PEU]

You need to heat it to 800~850C and then let it cool very slowly, otherwise D2, an air hardening steel, will re-harden. A way to cool it slowly is right after heating it throw it inside a big bucket of ashes and let it cool there for hours. That, or what Stacy said


Pablo

 

[samuraistuart]

I am not a D2 guy....but doing some research to help you out.....D2 is not a great candidate for re-hardening. The grain growth from re-austenitizing can be bad. Nathan mentioned that you can bring it up to sub-critical a few times with an air cool in between. This will make it somewhat more workable...but the heat treat to harden it after the anneal may be give you problems. When you get an oven, you can heat it to about 1650F and let it cool down to 1000F at a rate not to exceed 50 degrees per hour. But then you have to re-harden it....and from what I gather it might be problematic. Good luck with that one!

 

[Stacy E. Apelt - Bladesmith]

You need to heat it to 800~850C and then let it cool very slowly, otherwise D2, an air hardening steel, will re-harden. A way to cool it slowly is right after heating it throw it inside a big bucket of ashes and let it cool there for hours. That, or what Stacy said


Pablo

If he takes a piece of hardened D2 and heats it red with a torch and sticks it in a bucket of ashes, it will likely make a terrible knife. Additionally, how could he HT it later without an oven?

D2 is not a steel to fool with. Previously hardened D2 is even worse. The HT is very specific and has no real wiggle room.

 

[Frank Niro]

About 35 years ago I used planer blades to make straight knives. I found it was easy to drill holes where needed but could never anneal them. I tried the ashes and lime and even perhaps a few more ideas I was told about. Frank

 

[Nathan the Machinist]

The trouble with D2 is it's like hotdogs. Different manufacturers are free to make it with different ingredients. One lot to another can behave differently, and one maker to another can be very different.

Some D2, on a second austenitization without full anneal, can develop finer grain (depending on the temperatures) and another piece subjected to the exact same heat history can experience explosive grain growth so bad it looks like fish scales. Done intentionally it's called prequenching, and the temperatures described in the literature I've seen are wrong and don't apply to all particular makers of D2.

If you can't do a proper anneal, and you can't properly evaluate your grain situation you're better off leaving it alone. An uncontrolled heat or cool, such as torch or ash, can cause different structures in a single piece that react differently in a subsequent heat.

 

[PEU]

If he takes a piece of hardened D2 and heats it red with a torch and sticks it in a bucket of ashes, it will likely make a terrible knife. Additionally, how could he HT it later without an oven?

D2 is not a steel to fool with. Previously hardened D2 is even worse. The HT is very specific and has no real wiggle room.

He asked how to soften it... The best advise now that I think more about it would be buy a new blank of easier to work steel, a high carbon like 1070~1095 or 5160, those are best for inexperienced users and very forgiving...


Pablo

 

[Lo/Rez]

Thanks for the replys. I will try to work with it as is.