Grade Summary: D2 is a high carbon, high chromium, air-hardening tool steel. It was formulated to combine excellent abrasion resistance and air-hardening characteristics and has become the tool and die standard against which other tool steels are measured for abrasion resistance, dimensional stability in hardening and air-hardening characteristics. When properly annealed, D2 has a machinability rating of 45 as compared to a 1% Carbon Steel rated at 100.
D2 has the minimum distortion in heat treatment as compared to other tool steels. When air quenched from the proper hardening temperature, this
grade can be expected to expand or contract approximately .0005 in. per in. Note: Distortion (bending, bowing and twisting) as well as part geometry can add to the variations in movement of a part being hardened.
Thermal Cycling: In order to avoid decarburization, this grade should be annealed and/or hardened in a controlled neutral atmosphere, vacuum or neutral salt furnace environment.
1. Anneal: Heat to 1650° F. Soak one and one-half hours per inch of thickness. Cool 20° F per hour to 900° F. Cool in furnace to room temperature.
2. Stress Relief of Unhardened Material: Heat slowly to 1200° to 1250° F. Soak for two hours per in. of thickness at heat. Soak, slow cool (furnace cool if possible) to room temperature.
- Preheat: Heat to 1250° F. Hold at this temperature until thoroughly soaked.
- Harden: Heat to 1850° F. Soak at heat for 45 to 60 minutes per inch of thickness. Soak sufficiently long enough to get all of the alloying elements into solid solution during the austenitizing cycle. Proper response to heat treatment will depend on this. Therefore, for items under one inch in thickness, soaking time should be 45 to 60 minutes minimum.
- Quench: Air quench to 150° F. Temper immediately.
- Temper: Double tempering is mandatory, three tempers are sometimes preferred. Soak for two hours per inch of thickness at heat. Air cool to room temperature between tempers. Double temper at the range of secondary hardness (900° to 960° F) strongly recommended.
Specimens were air quenched from 1850° F.
Typical Chemical Analysis: * C – 1.55 *Mo – .80 *Cr – 11.50 *V – .90
* Chemical Analysis will vary.
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