MICROSTRUCTURE AND PROPERTIES OF LASER-SURFACE HARDENED M2 HIGH-SPEEDSTEEL

In the present paper, the microstructure and properties of laser surfa ce hardened M2 high speed steel have been studied. The influences of p reheat treatment processes, post heat treatment processes and laser pa rameters on the properties of the laser treated zone are also investig ated. It was shown that the surface hardness and softening resistance of M2 high speed steel are evidently increased with laser surface hard ening. 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 la ser surface hardening. The grain size of laser hardened zone is much s maller than that of the traditional quenched high speed steels at diff erent quenching temperatures. The amounts of retained austenite and un dissolved carbides are decreased, and disperse carbides precipitate du ring laser surface hardening.