Effect of Arc Trajectory on Microstructure and Properties of Inconel 625 AlloyThick-Wall Parts by CMT Arc Additive Manufacturing

The thick-wall parts of Inconel 625 alloy were prepared by additive manufacturing technique using cold metal transition (CMT) arc as heat source. The microstructure and properties of the parts under oscillating and two-pass multi-layer arc trajectories were comparatively studied. The results show that spatter appeared during the additive manufacturing with oscillating arc trajectory, and the surface of the thick-wall parts was rough; no obvious spatter appeared during additive manufacturing with two-pass multi-layer arc trajectory, and the surface was smooth. The growth mode of dendritic crystals in the thick-wall parts was epitaxial growth, and there were secondary and tertiary dendrites in the dendritic crystals; the dendrite spacing under oscillating arc trajectory was smaller than that under two-pass multi-layer arc trajectory. The average tensile strength of the thick-wall parts under two-pass multi-layer arc trajectory was higher than that under oscillating arc trajectory. The anisotropy percentages of the tensile strength of thick-wall parts under oscillating and two-pass multi-layer arc trajectory were very small, which were 4% and 4.5%,respectively. The fracture type of thick-wall parts was ductile fracture.