Study of residual austenite in the surface layer of (M2) high speed steel hardened by laser

The amount and distribution of the residual austenite in surface layer of M2 high speed steel hardened by laser were investigated by transmission electron microscope and X-ray diffraction, It was shown that less residual austenite exists in laser treated M2 high speed steel compared with the traditionally quenched M2 high speed steel. The amount of residual austenite was decreased by an increase of the laser energy density, Numerous disperse carbide precipitates and larger amount of crystal defects existed in primary austenite grains. The residual austenite distributed heterogenously in the laser treated zone, The more residual austenite existed in the surface zone than that in the subsurface zone.