D2 Tool Steel

Discussion in 'Knife Steel Reference' started by Darrin Sanders, Dec 6, 2013.

  1. Darrin Sanders

    Darrin Sanders Moderator


    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.
  2. Mark Behnke

    Mark Behnke Well-Known Member

    Hope I'm not being to dumb but what is meant by equalize.
  3. cnccutter

    cnccutter Well-Known Member

    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.

  4. Darrin Sanders

    Darrin Sanders Moderator

    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.
  5. cnccutter

    cnccutter Well-Known Member

    Interesting, can you expand on what it does/purpose in heat treating the steel?..

  6. Darrin Sanders

    Darrin Sanders Moderator

    It just insures that the steel is at the same temp. as the kiln before moving to the next temp..
  7. me2

    me2 Well-Known Member

    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.
  8. Joel Brazzoni

    Joel Brazzoni Well-Known Member

    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.
  9. Brad Lilly

    Brad Lilly Moderator and Awards Boss

    Just curious as a good temperature to temper a liner lock spring made from D2?

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