The influence of laser remelting on the microstructure and mechanical properties of molybdenum manufactured by powder bed fusion

Pure molybdenum materials fabricated by Laser Powder Bed Fusion (LPBF) generally suffer from low density and porosity defects, which significantly affect their mechanical properties. As a common scanning strategy in the LPBF process, remelting plays an important role in improving the density and mechanical properties of refractory metals. This study investigates the differences in microstructure and mechanical properties between pure molybdenum formed by remelted and non-remelted processes. By comparing density, defects, microstructure, Vickers hardness, and tensile properties, the influence of the remelting process on the formation quality of molybdenum and its mechanism are comprehensively analyzed. The results show that, the defects are significantly reduced and the density is markedly increased after remelted. The grain size and Vickers hardness parallel to the building direction are also increased. Meanwhile, the strength is decreased, but the elongation after fracture is increased. The research results provide a reference for the performance regulation of additively manufactured molybdenum and its alloys.