Influence of laser tempering on the characteristics of surface layers of tool steels

A study was made of the kinetics of precipitation of martensite and retained austenite in the course of laser tempering of structures and zones formed by laser quenching in U8 carbon steel and of KhVG, 9KhS, and Kh12M alloy steels with different initial structures and phase compositions. The selectivity of the laser tempering process revealed a degree of structural and phase transformations in these steels, resulting in changes in the characteristics of the surface layer. Laser tempering in combination with laser quenching was found to influence greatly the formation of residual stresses in the laser interaction zone and could therefore be used effectively to tackle the problem of crack formation during laser thermal hardening of the surface.