焊前固溶处理对SLM-AlSi10Mg合金激光焊孔隙缺陷的影响

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

针对选区激光熔化成形AlSi10Mg铝合金焊接过程中氢气孔敏感性高的问题,采用固溶脱氢与真空固溶脱氢的方法对比了脱氢处理对合金激光焊接接头孔隙缺陷的影响,分析了不同状态下激光焊焊缝气孔分布、组织演变及力学行为。结果表明,固溶处理能够有效减少选区激光熔化成形AlSi10Mg铝合金激光焊焊缝气孔率,且真空固溶处理效果最好,气孔率从沉积态激光焊接焊缝的2.646%降到真空固溶态焊缝的0.14%;通过对接头组织的演变与基板物相形态、成分的变化分析阐述了孔隙出现的原因,揭示了真空热处理是解决由于基板中预先存在的较高含量的氢导致焊缝氢气孔形成的有效方法。固溶后母材硬度明显下降,各试板焊缝的平均硬度(HV)为784MPa,较为一致;固溶态试板焊接接头抗拉强度为143 MPa,低于沉积态接头,但延伸率增加到了24%,表现为韧性断裂特征。

Given the high sensitivity of hydrogen porosity in the welding process of ASiloMg 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 AiSiloMg 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.