Microstructure and Properties of Laser Cladding Co-Based Alloy Coatings

Abstract

The Co-based alloy coatings were successfully fabricated on H13 steel by Nd:YAG and CO2laser. The microstructure and properties of the laser cladded coatings were compared and analyzed by SEM, EDS, XRD and microhardness tester. The results show that the excellent metallurgical bonding has formed at the interface between substrate and laser cladded coatings. Cellular crystal at the bonding zone, cellular dendrite at the central zone and reticular equiaxed crystal near top surface were observed in Nd:YAG laser cladded coating, while the typically hypoeutectic character was found in CO2laser cladded coating. Phase constituents of both coatings are mainly composed of Cr23C6, Co3Mo2Si, MoC, FeCr and γ-Co. The microhardness of H13 steel is greatly improved by laser cladding, however the microhardness of the CO2laser cladded coating is even higher than the Nd:YAG laser cladded coating.