Looking for a simple method of tempering D2 steel for woodworking knives

A. Hello Marvin!

Well, D2 is a bit of a different beast than O1. The austenitizing temperature is higher, 1850 °F rather than 1450 °F, to allow more dissolution of the chrome carbides. After the FORCED AIR quench (not oil like O1) D2 is usually given a double or triple temper, at either 350 °F, 525 °'F, or 950 °F, depending on where you want to be on the hardness / toughness tradeoff. Some of us deep freeze before the temper as well, to maximize the martensite conversion.

I'm a bit confused when you say you want the increased toughness and stain resistance of D2. D2 is a cold work tool steel, and will easily harden to 60-64 HRC; but it is really brittle. It is chock full of carbides, which give it wonderful wear resistance, and a edge to die for (well, not literally). But its toughness is lower than that of O1. The major pseudo-toughness advantage D2 has is that it is air hardening, so there will be less distortion on quenching -- less chance of quench cracking. Further, while D2 does have 12% chromium in it, most of that amount is tied up as carbides, so it doesn't buy you corrosion resistance.

But back to your question- assuming you can get as high as needed (1850 °F), then D2 should be even easier to harden than O1. You'll want to make some provision for surface oxidation, by either using an inert gas or a protective bag. And if you've put the time into it that many skilled bladesmiths do, you may want to consider using a commercial heat treat, at least should you make a Master Work.

Timken Steel offers some data sheets on their D2, and also have some fine heat treat recommendations. Uddeholm and Carpenter are other steel companies with a lot of information on the web, at your fingertips. I'd also strongly recommend you read the postings at rec.crafts.metalworking, the newsgroup frequented by many bladesmiths. Although I am curious about how you came to post here at finishing dot com. . .

Good luck!

A. As usual, an excellent response from Lee. The baggie that he referred to is a special stainless steel foil bag. The part has to be wrapped with the least possible air (oxygen) to hold down the oxide layer. D-2 is really tough to work compared to O-1, IE: it requires patience.

Look into the properties of S-2, a shock resistant steel that will take a lot of abuse and is decent to work. I have no idea of how well it will hold a really fine edge.

A. Crucible Service Centers are tool steel distributors and have an office out in Davenport and outside Romeoville, and ask for one of their Selectors (the infamous Orange Book). It is full of tool steel information. All steel mentioned have different attributes, to get the maximum benefit, you should be prepared to balance the properties you need with the conversion methods you have available. There ought to be plenty of tool & die shops that have their own small heat treating furnaces, they could probably put your work in with theirs for a minimal charge (D2).

Q. D2 air quench? For the air quench of the material, this is at room temp. correct? Is it forced/moving air or still air?

A. Okay, what everybody fails to tell you is when removing D2 from the s.s. wrap at 1850 °F you should cool with a fan or it will not get hardness specs; it will be spotty; so don't just let it sit in the still air, use a fan to air quench D2.

A. Hi, Avinasha. D-2 is not a stainless steel, it is a carbon steel and will rust like one. Lee knows way more than me about this, and he says most of the chromium content is tied up as carbides and doesn't afford corrosion resistance. Good luck.

Regards,