Microstructure and Mechanical Properties of Sn58Bi Components Prepared by Laser Beam Powder Bed Fusion

Abstract

As a low melting point alloy, Sn58Bi alloy plays a unique role in many fields. However, the brittleness of Sn58Bi alloy is a limitation that has to be addressed for wider applications. According to previous studies, third element addition is favorable for improved ductility, which is attributable to structure refinement. Therefore, laser beam powder bed fusion technology was adopted to prepare Sn58Bi alloy components. Additionally, the as-printed specimens presented more refined structures compared to the as-cast specimen, so they showed better plasticity. The Sn58Bi alloy showed excellent formability when specimens were prepared by LBPBF between 40–80 W. The density of specimens nearly remained stable above laser power higher than 40 W, and CT scanning could not detect internal defects, so the Sn58Bi alloy specimen was likely to be well fabricated at high laser power. Within the laser power range of 40–80 W, with the variation of laser power or scanning velocity, the laser energy density changed accordingly, and the mechanical strength of specimens was improved with the increase of laser power density. This strength change was probably related to the microstructure evolution and internal residual stress in the printing process.