Laser Surface Hardening of Graphite Cast Iron

Abstract

Two types of graphite cast iron are evaluated. The effect of laser surface hardening is compared using metallographic analysis of the microstructure and measurement of hardness profile. Conditions of the hardening were the same for both analyzed materials. The alloys that were compared are: cast iron with lamellar graphite EN GJL-200 and cast iron with nodular graphite EN GJS-700 CuNi. Microstructure of tested cast irons was pearlitic-ferritic. Laser surface heat treatment caused formation of martensitic layer. The depth and structural compositions of hardened layers do differ. In the case of gray cast iron the higher hardened depth was achieved and in the case of ductile cast iron the higher hardness was observed.