Microstructure and mechanical property of laser powder bed fusion additive manufactured Al-10Si-Mg alloy

Laser powder bed fusion, an additive manufacturing process, is suited to fabricate the aluminum parts with complicated shapes for aerospace and automotive industries. Laser powder bed fusion of aluminum alloys often leaves internal defects in the parts, but formation mechanism of internal defects has not been fully understood. In this study, effect of laser irradiation condition on internal defect and microstructure of the parts was examined to obtain the fundamental knowledge of the defect formation during laser powder bed fusion of Al-10Si-Mg alloy. Density of the internal defects was high in the parts produced at the low and high energy densities, while there were almost no defects in the part produced at meddle (appropriate) energy density. The high energy density resulted in spherical defects like blowholes, while the low energy density caused polygonal shaped defects. Formation of the polygonal shaped defects could be explained by insufficient melting of powders at the low energy density because width of the melt pool was very narrow. The microstructure was coarser at the higher energy density. The tensile strength and elongation were strongly affected by the amount of internal defects in the part, rather than the microstructure. © 2024 Japan Light Metal Welding and Construction Assoc.. All rights reserved.