D2 steel is an air-hardening, high-carbon, high-chromium tool steel. It has high wear and abrasion-resistant properties. It is heat treatable and will offer a hardness in the range of 55-62 HRC, and is machinable in the annealed condition. D2 steel shows little distortion on correct hardening. D2 steel’s high chromium content gives it mild corrosion-resisting properties in the hardened condition. Cold-work tool steels include the high-carbon, high-chromium steels or group D steels. These steels are designated as group D steels and consist of D2, D3, D4, D5, and D7 steels. These steels contain 1.5 to 2.35% of carbon and 12% of chromium. Except for type D3 steel, all the other group D steels include 1% Mo and are air hardened. Type D3 steel is oil-quenched; though small sections can be gas quenched after austenitization using a vacuum.