Microstructure Modification of Tool Steel X38CrMoV5-1 by Fibre Laser

In the present work, we investigate the influence of laser radiation on the evolution of microstructure and wear resistance of X38CrMoV5-1 tool steel in hardened and tempered condition. The microstructure of the laser surface hardened zone consists of fine and coarse grained carbides (M23C6, M7C3, MC or M2C) which are dispersed within martensite matrix. On the other hand, the laser melted microstructure is characterized by martensite, retained austenite and fine carbides precipitated in the inter-dendritic zone. The laser surface affected zone microstructure exhibits the enhanced hardness in the range from 857 to 775 HV in comparison with quenched and tempered conditions (720-655 HV) and decreases from the surface to the soft zone with a typical hardness of 530 HV. The wear resistance of the laser treated samples is investigated by “ball on disc” method, which shows a significant improvement as compared to that in quenched and tempered condition.