Microstructure and mechanical properties of GH5188 superalloy additively manufactured via ultrasonic-assisted laser powder bed fusion

Abstract

The GH5188 superalloy was fabricated by ultrasonic vibration-assisted laser powder bed fusion (LPBF). The effect of ultrasonic vibration on surface roughness, relative density, and microstructure of ultrasonic vibration-assisted LPBF-fabricated GH5188 superalloy were analyzed. The mechanical properties, including tensile properties and microhardness of the fabricated samples, are evaluated and compared between ultrasonic vibration-assisted LPBF and LPBF without ultrasonic vibration. The results show that ultrasonic vibration significantly refines the grain and inhibits the preferred orientation of texture. The average grain size decreased from 80.91 µm to 53.02 µm with ultrasonic vibration. The maximum multiples of uniform distribution (MUD) value decreased from 10.370 to 7.696. The microhardness, tensile strength, yield strength, and elongation increased by 4.49%, 2.6%, 4.6%, and 5.6%, respectively. Grain refinement, inhibition of texture preference orientation, and the improvement of overall properties demonstrate the feasibility of ultrasonic vibration to improve LPBF forming. The investigation in this work will establish a potential way to eliminate the anisotropy and improve the quality of LPBF.