Intergranular corrosion characteristics of high-efficiency wire laser additive manufactured Inconel 625 alloys

The subgrain segregation of Inconel 625 components fabricated using high-efficiency wire laser additive manufacturing and its effect on the intergranular corrosion characteristics were investigated. The subgrain segregation occurs between the dendrite core and inter-dendritic region, which increases the lattice distortion energy and lowers the potential. The generated micro-corrosion couple between the dendrite core (cathode) and inter-dendritic region (anode) accelerated the dissolution of the latter. Moreover, the dispersed (Nb, Ti)N precipitates and instability of the passive film in the inter-dendritic region deteriorate the corrosion resistance. These results significantly advance the composition and additive manufacturing design of corrosion-resistant nickel-based superalloys.