Microstructure and interface characteristics of laser-clad cobalt-base coating on the surface of a nickel-base alloy

Presetting Stellite X-40 alloy powder on the surface of a K403 casting superalloy plate was laser remelted to obtain a protective cladding layer. The microstructures, interface characteristics and influence of defocusing amount on the microstructure were investigated. The results shown that, a sound bonding between the cladding layer and the substrate was obtained, and no cracks or pores were formed in the cladding layer. The molten pool depth when a negative defocusing amount was used was larger than that when a positive defocusing amount was used. The structure of the cladding layer was not uniform but stratified into several layers. Equiaxed grain was observed in the central area of the cladding layer, and a transition layer existed between the cladding layer and the substrate. An abnormal distribution of Al, Ti elements was detected and the concentration of Al, Ti is much higher than that of the cladding layer and the substrate.