Tool steels hardness

Note: Sizes over 3 inches Tempering: Temper immediately after quenching. Hold at temperature for 1 hour per inch To minimize internal stresses in cross sections greater than 6 inches Cryogenic Treatment: Some prefer to do cryogenic treatment as an extension of the quench from the austenitizing treatment.

Others prefer to cryogenically treat after tempering. Continue cooling to ambient temperature in the furnace or in air. The resultant hardness should be a maximum of HBW. The minor load establishes the zero position. The major load is applied, then removed while still maintaining the minor load. The difference between depth of penetration before and after application of the major load is used to calculate the Rockwell hardness number.

That is, the penetration depth and hardness are inversely proportional. The chief advantage of Rockwell hardness is its ability to display hardness values directly. Department of Energy, Material Science. January William D. Callister, David G. Eberhart, Mark ISBN Gaskell, David R. Introduction to the Thermodynamics of Materials 4th ed. Taylor and Francis Publishing.

Ideal grade for maximum production runs. Superior machinability. Excellent wear-resistance, high compressive strength, and deep hardening properties. Most widely used in the D series. Oil Hardening. Easy to machine. Good abrasion resistance.

Most widely used in O series. Shock resistant tool steel. Used in applications that require high toughness and resistance.