Microstructure and mechanical properties of Inconel-625 slab component fabricated by wire arc additive manufacturing

Wire arc additive manufacturing is a promising reliable free-form fabrication technique suitable for producing large-scale components that feature a very low buy-to-fly ratio. This research work is aimed to fabricate a rectangular prototype Inconel-625 alloy slab using a robotic metal inert gas welding system. The microstructure and mechanical properties of as-deposited and solution-annealed (SA) alloys were investigated. It was found that the as-deposited alloy exhibited a columnar dendritic structure and the presence of intermetallic phases such as the Laves phase, NbC and carbides were observed in the gamma-nickel matrix. In SA deposit, the intermetallic phases were dissolved in the NiCr-matrix and the secondary carbides M23C6, M6C were also observed in the microstructure. It was found that the ultimate tensile strength and microhardness of the as-deposited alloy were higher than that of SA deposit.