Effect of different topologies on microstructure and mechanical properties of multilayer coatings deposited by laser cladding with Inconel 625 wire

Abstract

Different topologies of clad coatings mean different cladding strategies and cyclic thermal histories. In this study, two types of Inconel 625 multilayer coatings with parallel topology (The cladding direction between adjacent layers was parallel.) and perpendicular topology (The cladding direction between adjacent layers was perpendicular.) were fabricated respectively on 316 L substrate using an off-axis wire cladding system. The effects of different topologies on microstructure and mechanical properties of the coatings were investigated. The finite element (FE) model was adopted to predict the cyclic thermal histories in different topologies. The results showed that morphologies of the two topologies both presented good surface finish and free of crack and pore defects. Compared with perpendicular topology, for coatings with parallel topology, columnar dendrites in the upper and lower layers exhibited relatively consistent orientation since they complied with the movement direction of heat source. The parallel topology also exhibited better mechanical properties along the cladding direction due to the uniform cyclic thermal history. Although Laves phase pinned the migration of grain boundaries, it was also the main cause of producing microvoids that led to the fracture.