How to soften D2 without a kiln?

Salem Straub

Salem Straub

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Oct 20, 2008
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I obtained about 20 feet of 5/32" x 2" D2 stock recently. Problem is it's in new planer blade form and I do not have a knife kiln. Anyone have a forge-type method of getting this stuff to a reasonable softness to work with? I know a true anneal takes more than I have.

Or do I just need to suck it up and send it to Peter's for annealing? I got the blades in trade for a hunting knife, so I'd still be ahead.

Thanks for your thoughts.
 
Send it to Peters' for a full anneal.

I don't have the numbers in front of me, but a highly-alloyed air-hardenable steel like D2 is going to require very high temps, with a pretty long soak at temp, then a rather slow, controlled cooling cycle to get it back to "soft". Especially if you have 20' of it, there is no way to anneal or HT it in your own shop, cheaper or better than the pro shops can.
 
I'd look locally if I were you. The workers there might throw it in with a big batch from a regular customer for a case of beer or so. Even if you have to pay, it beats shipping it across country.
 
Let me know what you figure out Salem, I can probably do it for you.
 
Short answer: take it up to just barely red hot (sub critical) and let it cool. Do this a few times and it will be more workable. However, subsequent heat treat will be hit or miss. It depends on what temperature it was originally austenitized, which you have no way of knowing.

Long answer: depending on how it was heat treated, it is possible to get massive grain growth in a second austenitization with this steel. HSS is the same way. For these complex steels, the carbides that pin the grains can get pretty small during the original heat and only stop dissolving once the matrix hits saturation, which is primarily a function of the temperature used. On a second heat, they're small enough that some completely dissolve before the matrix reaches saturation, leading to massive grain growth on the second austenitization. For best results it needs to be reset with a full spehoridized anneal, which requires time and temperature control. Short of that, your heat treater needs to know the steel already has a heat on it and to use a lower temperature, perhaps 1800, as a hedge. And while he can measure the resulting hardness, accurately measuring the grain size is much more difficult. I wouldn't mess with it.

D2 likes to be a pill. I love/hate it.
 
Can't help with the D2 but I am just curious why no kiln yet Salem?
You being full time I would think this would be high on the 'to buy' list.:(
 
Patrice, it is high on the list. I've been forge heating for quench- which works fine for hamons, carbon steels. My stainless stuff gets farmed out for HT. I would love to have an Evenheat, though.

Actually, being full time slows down my shop building in many ways. I don't make much money as a knifemaker (yet.)

Carl, I live in BFE. A good suggestion, if I lived anywhere else. Thanks.

Ben, I really appreciate that. I think I'm gonna get Peters to do it, after all.

Nathan, thanks. I really like your writings about D2 in general, if fact before working with this stuff much I was going to PM you for HT company recommendations. Your objection to snap tempering before cryo is an eye opener. It's good to know that there is a very good reason for re - full spheroidizing it.

I called Peters up to pay them for past services, and asked Brad S. for a quote on annealing 20 lbs. of D2. $50, he tells me. Totally worth it, that's what I'm going to do. Flat rate both ways. I'm going with James T. on this one.

Thanks all, for helping me decide.
 
Almost everything I really know about D2 came from Nathan. Now, if I knew everything he really knows, I'd be rockin' :)
 
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