Effects of circular beam oscillation on microstructure, mechanical and electrochemical corrosion properties of laser melting deposited Inconel 625

Circular oscillating laser was used as a heat source for additive manufacturing to fabricate Inconel 625 alloy. This study focused on the influences of the circular beam oscillation on the microstructure characteristics, tensile properties, and electrochemical corrosion performances of Inconel 625 alloy. The stirring effect of the circular beam oscillation on the molten pool interrupts the formed dendrites, and the partially fractured grains acted as nuclei to promote the growth of equiaxed grains. The average grain size of circular oscillation decreased from 111.51 to 66.49 mu m. The cooling rate of the molten pool of the circular oscillation was faster, and the Refractory elements were captured by the gamma matrix before Laves phase was formed, thus reducing the Laves phase content in the coating with circular beam oscillation by 50.66 %. The finer grains and lower Laves phase content reduced the crack source, and the ultimate tensile strength and yield strength of circular beam oscillation were increased by 56.95 % and 128 % respectively. The lower grain size of circular beam oscillation leads to the increase of corrosion spots, resulting in the decrease of corrosion current density by 62.3 %, which weakens the corrosion resistance.

Automated summary

This study used circular oscillating laser as a heat source for additive manufacturing of Inconel 625 alloy. It found that circular beam oscillation reduced grain size, improved mechanical properties, and decreased corrosion current density, but also lowered corrosion resistance.