Control of the microstructure and mechanical properties of CMT arc wire additive manufactured Inconel 625 alloy by solution treatment

Inconel 625 alloy samples prepared by cold metal transfer arc additive manufacturing (CMT AA) were solution treated at different temperatures. The microstructure and mechanical properties of the solution treated Inconel 625 alloy were investigated. The results showed that the as-deposited sample primarily consisted of columnar dendrites growing along the deposition direction. The matrix structure was predominantly γ-Ni austenite phase with a large number of second phases, including Laves phase and tiny MC particles distributed inside the grains and on grain boundaries in the form of “blocks” or “chains”. When the solution temperature was below 1000 ℃, the solution treatment had little effect on the microstructure and properties of the alloy due to the slow dissolution of Laves phase and carbides. As the solution treatment temperature increased to 1200 ℃, the second phase carbides dissolved, and the grains grew sharply with many twins. The hardness and tensile strength of the alloy decreased to some extent. The yield strength decreased, and the elongation increased significantly.