Effect of Prewelding Solution Heat Treatment on Pore Defect in Laser Welding of AlSi10Mg Alloy Prepared by Selective Laser Melting

Given the high sensitivity of hydrogen porosity in the welding process of AlSi10Mg aluminum alloy formed by selective laser melting, the effect of dehydrogenation treatment on the pore defects of alloy laser welded joints was analyzed by solid solution dehydrogenation and vacuum solid solution dehydrogenation methods under different states as well as the pore distribution, microstructure evolution, and mechanical behavior of laser welded seam. The results show that the solution treatment can effectively reduce the porosity of AlSi10Mg aluminum alloy laser welded seam formed by selective laser melting. Vacuum solution treatment has the best effect, which reduces the porosity from 2.646% of the deposited state laser welding seam to 0.14%. The reasons for the appearance of pores were explained by analyzing the evolution of the joint structure and change in the phase morphology and composition of the substrate. It is revealed that vacuum heat treatment is an effective method to solve the problem of pore formation in the weld due to the high content of hydrogen pre-existing in the substrate. After solid solution, the hardness of the base metal decreases significantly, and the average hardness (HV) of the welds of each test plate is 784 MPa, which is relatively consistent. The tensile strength of the welded joint of the solid solution test plate is 143 MPa, which is lower than that of the deposited joint, but the elongation increases to 24%, showing characteristic of ductile fracture.