A comparative study on microstructure and properties of Inconel 52M overlays deposited by laser beam and GTA cladding

The current study investigates the overlays deposited by laser beam (LB) and gas tungsten arc (GTA) cladding with Inconel 52M filler wire in nuclear power plants. The effects of the deposition methods on the cross section profile, microstructures, and mechanical properties of both overlays are studied using optical microscope, scanning electron microscope (SEM), tensile and impact test and microhardness measurements. Experimental results show that LB cladding with higher wire feed rate improves the deposition efficiency as compared with GTA cladding. The microstructure of the LB clads consists of cellular and columnar dendrites, and Nb-rich spherical particles are precipitated in the interdendritic regions, while the equiaxed dendrites are dominant in the GTA clads. The microhardness of the GTA clads is 20-30 HV higher than that of the LB clads. Furthermore, the tensile strength, toughness, and elongation of the LB clads decrease in comparison to the GTA clads. The deep penetration of the LB clads resulting in a wave shape of each pass and high dilution does not benefit the mechanical properties as compared with the GTA clads.