The Microstructure Inhomogeneity of the Laser Surface Hardened Layers

Abstract

Much attention has recently been focused on the microstructure inhomogeneity problems of the laser surface hardened layers.The GCr15 steel specimens were treated through laser transformation hardening technology. Rapid heating of austenite transformation and microstructure inhomogeneity was studied.The nouniform austenitic formation and the microstructure inhomogeneity problems is caused by uneven temperature field. The input power fluctuations and laser beam model also affect the quality of the laser quenching. Hardness value fluctuation is due to the uneven microstructure of the laser hardened layer. The results show that the grain size of laser hardening area and the distribution of carbides is not uniform. In the rapid heating cases, the atomic difusion process of carbon and alloy elements is not sufficiently, this causes no uniformity of the distribution of carbon and alloy composition .