MICROSTRUCTURE AND PROPERTIES OF LASER-SURFACE HARDENED M2 HIGH-SPEED STEEL

In the present paper, the microstructure and properties of laser surface hardened M2 high speed steel have been studied. The influences of preheat treatment processes, post heat treatment processes and laser parameters on the properties of the laser treated zone are also investigated. It was shown that the surface hardness and softening resistance of M2 high speed steel are evidently increased with laser surface hardening. The M2 high speed steel which is quenched at 1220 degrees C and triple tempered at 560 degrees C for 3 h has higher hardness after laser surface hardening. The grain size of laser hardened zone is much smaller than that of the traditional quenched high speed steels at different quenching temperatures. The amounts of retained austenite and undissolved carbides are decreased, and disperse carbides precipitate during laser surface hardening.