Oil quenching D2?

[flatgrinder]

I noticed that 154CM and S30V can be oil quenched.

Anyone oil quench D2? Can you gain a few points of extra hardness using an oil quench over air quenching? The reason I'm asking is that I don't have access to liquid nitrogen. So ... would an oil quench, into the freezer overnight and then followed by a double temper produce a blade that will perform respectably?

Thanks! :thumbup:

P.S. I heard Bob Dozier doesn't do a cryo treatment, not sure if that's true, but the man knows what he's doing with D2. Anyone know if he air quenches or does an oil quench? And for the record, if he does use liquid nitrogen or not?

 

[Nathan the Machinist]

I really like D2

I know that some knowledgeable folks don't freeze it, but with a lower temper (450) ya know it's gonna have a lot of retained austenite, and with cryo and a low temper you can get 63 ish rockwell numbers, which is a brilliant performer. I recently made a batch like that, and it took a very good edge, had outstanding edge retention in cardboard and could be hammered through 1/4" brass in one blow and cut small nails with practically no edge flattening or chipping. Really great stuff, D2. But it is my opinion that the freeze is important.

I have oil quenched it, but I normally plate quench it. I don't know if oil will get it harder or not. I tend to think perhaps a tad, but you increase your warping and mess for little gain. You might get a tad better corrosion resistance with the faster quench.

Look into dry ice and acetone. A lot of grocery stores have dry ice. Don't do a snap temper, go from the plate, to water, to ice.

I suggest staying away from the secondary hardening hump. You're getting weaker martensite and more carbide, not the best for edge stability IMO.

 

[Sam Salvati]

Wouldn't a multiple temper convert any retained austenite?

 

[AcridSaint]

Plate quench it, oil won't do anything extra for you.

 

[Nathan the Machinist]

Wouldn't a multiple temper convert any retained austenite?

Not at lower tempers, and the higher tempers have their down sides

 

[Nathan the Machinist]

A mistake that is easy to make with D2 is to under soak. A common misconception is if the recommended hold time is 30 min per inch of section, then a 1/8" section only needs a few minutes, which is not the case. In fact, I'm not so sure about only 30 min. I recommend a 40 min soak for a blade in D2.

Obviously, this much time at high temp is going to cause a lot of decarb, so foil is important, which is another good reason to plate quench. Make sure the seams are safely out of the way and won't interfere and you can quench directly through the foil with plates.

 

[mete]

Austenitizing temperature is important .If you keep it to the lower side of the recommended range you'll have less RA.30 minutes ought to be enough.There's no sense in oil quenching when plate quenching is so convenient. You'll never get rid of all the RA so you'll have to experiment to get the best properties for you.

 

[jlmetcalf]

D2 has a secondary hardening "nose" around 975F which will yield about RC61 (depending on austenizing temp). These high tempers will also result in the conversion of RA which is why multiple tempers are required ( the second one tempers the martensite created by the first).

If you use the high temper you get the benifit of austenite conversion plus the ability to resist softening if you get the blade hot during finish grinding. However, you loose toughness and corosion resistance.

If you cryo to convert the RA and temper twice at 500F you get max toughness and corosion resistance. The only thing you loose is the ability to get the blade hotter than 500F during post HT grinding.

Jim