Complex bulk-surface hardening of materials using a highly concentrated heat source

1. The complex bulk-surface hardening of the steels investigated using a highly concentrated heat source is an effective means of regulating their structure and crack resistance. 2. The heat resistance of steels hardened by a highly concentrated heat source can be increased by the use of preliminary bulk quenching (as a result of the formation of a natural soft interlayer — tempered zone) and/or subsequent bulk tempering (as a result of relaxation of internal structural microstresses). 3. Surface hardening by a highly concentrated heat source is an effective means of improving the crack resistance of components that operate in the bulk-quenched state; this is explained by a significant increase in the dispersity of the martensitic structure, and, as a result, by a qualitative change in the failure micromechanism. 4. The highest values of the crack-resistance characteristics of the steels investigated were obtained for the following combinations of heat treatment: bulk quenching+plasma hardening+tempering at 300°C for steels 30KhGSA and 45; and initial state+plasma hardening+tempering at 300°C for steels 9KhF and 150KhNM.