Selective surface hardening by laser melting of alloying powder

Microlayer surface hardening process by laser melting of Fe–Ni–Cr powder with AISI D2 tool steel surface has been investigated in this study. In distinction from the conventional processes of laser surface hardening, laser microlayer hardening involves hardening of target surface to a shallow depth. The melted powder to a depth required for hardening is subsequently self-quenched at a high rate of cooling by heat conduction into the substrate. In this study, parametric study for surface hardening is performed by 200 W fiber laser system. The single line bead was fabricated with various laser parameters and the quadrangle shape was analysed by optimised process parameters. The effects of laser power, scan rate and layer number on the hardness profile are investigated. From the analysis results, operational guide for laser surface hardening with metal powder will be suggested to get surface of target depth with desired hardness.