Grain refinement and mechanical properties improvement of Inconel 625 alloy fabricated by ultrasonic-assisted wire and arc additive manufacturing

Additive manufacturing (AM) of metallic materials usually results in columnar grains that grow epitaxially along the building direction, which usually results in anisotropy of mechanical properties. This common phenomenon is a severe challenge to the engineering application of AM components. Herein, we use ultrasound to assist the wire and arc additive manufacturing (WAAM) process of Inconel 625 alloy. The results show that ultrasound successfully breaks the growth of columnar grains and promotes the transformation from columnar grains to equiaxed grains. At the same time, the orientation texture is eliminated and the grain orientation tends to be a random distribution. The refinement of grain structure significantly increased the YS of Inconel 625 (13.2% and 23.8%) and reduced the anisotropy. In addition, the cavitation effect and convection of ultrasound increased the molten pool temperature and reduced the temperature gradient, which led to a significant decrease in the Nb content in the Laves phase. This exciting result is expected to be applied to alloys that are prone to columnar grains in WAAM. •Inconel625 alloy was innovatively fabricated by ultrasonic vibration assisted wire and arc additive manufacturing.•The segregation degree of Nb content in Laves phase decreases remarkable after ultrasonic vibration•Ultrasonic promoted the columnar grain to equiaxed grain of Inconel625 manufactured by wire and arc additive manufacturing, and the anisotropy was significantly reduced.