Hardening and tempering of tool steels and high speed steels

A: Products for the heat treatment of tool steels

The term hardening means a heat treatment process which consists of heating through and austenitizing components, followed by quenching. The higher the alloying content of the steels the lower the thermal conductivity. Therefore, in the heat treatment of tool steels and high speed steels, special care should be taken that the components are given a uniform and mild heating through, spread over several preheat stages.

B: Immersion time of HSS at hardening temperature
(German Standard Specification DIN 17350)

If the heating through is done too quickly, or if the holding times at the individual preheat stages or at austenitizing temperature are too short, stresses will occur due to the differences in temperature between case and core. This can cause cracking or even fracture of the component.

The diagrams on this page show typical heat treating sequences C in the hardening of tool steels and high speed steels, the respective Durferrit product A and the holding times of high speed steels at austenitizing temperature C.

C: Time/temperature profile for the treatment of tool steels

 
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