D2 Tool Steel

#1
Carbon-1.50-1.55
Chromium-11.5-12.0
Manganese-0.30-0.50
Molybdenum-0.75-0.90
Silicon-0.25-0.40
Vanadium-0.80-0.95

D2 is an air hardening tool steel. The chromium content makes it "almost" stainless. It can be quenched in still air but most knifemakers quench between two 1" thick aluminum plates. It needs to be heat treated in an oxygen free environment. This can be accomplished with blade coatings, foil wrap, or environmentally controlled kilns. It is a popular steel and makes good knives. The following process is a good starting point for heat treating D2. Your equipment may require different temps. & times so feel free to experiment.
1. Heat to 1100-1200 and equalize.
2. Heat to 1400-1450 and equalize.
3. Heat to 1825-1875 and soak for 30-45 miuntes.
4. Quench in air or between quench plates to 150 degrees.
5. Temper twice for 2 hours each time. Temper between 400 & 1000 depending on the application.

D2 benefits from a sub-zero freeze or liquid Nitrogen cryo but it isn't necessary. If either is used it must be followed by a tempering cycle.
 

cnccutter

Well-Known Member
#3
My guess is he meant normalize. bring it up to temp and bring out and let cool to black color... bring it up to temp and let cool to black. Its a stress relieving method.

Erik
 
#4
Normalizing is a different process. When I say equalize, I mean let the kiln "settle" at the target temp. before moving to the next temp.. You could also just do a 5 min. soak at each temp. to be sure everything is equalized.
 

me2

Well-Known Member
#7
The big reason for equalizing and preheating is to minimize thermal stresses due to different temperatures within the same piece. Another reason is rapid heatinreg will temporarily increase the critical temperature. Rapid heating without time for equalization can result in incomplete austenization. I dont know the numbers, and I dont think its much to worry about, but it does happen. I suspect its really only an issue with things like induction hearing or salt heating. IMO, this goes beyond the scope of this forum, and can be continued in the heat treating forum if anyone wants to do so.
 

Joel Brazzoni

Well-Known Member
#8
From my limited experience Cpm D-2 is really nice to work with, it grinds fairly easy, takes a nice polish and holds an edge better than 0-1 at the same hardness but is not as tough.
I think it's a great steel for smaller knives that won't see impact.
I'v had a critical failure on a large chopper with Aristocrat D-2 at 60rc.
 
#10
Depending on how thick the linerlock is i would temper to 400f so that it fails plastically not brittle, but i think more important would be to use the lower austenitization temps and make stress risers very very gradual... but this is purely from a theoretical point of view and not an experience point of view... the other questiin is do you cryo or not? On second thought it makes no difference unless you temper high... in which case it is probably better not to do it... toughness for these class of steels are higher in the low temper zone... my blades get cryo and tempered between 300 and 350