Effect of Er and Zr addition on laser weldability of AlSi10Mg alloys fabricated by selective laser melting

The additive manufactured (AM) parts of aluminum alloys have been widely used in defense, aerospace, automotive and other industries. There is a growing demand for joining or repairing of the AM parts of aluminum alloys using welding technology. However, the problems of high porosity and joint softening are occurred when welding of aluminum alloy AM parts, which have become technical bottlenecks that need to be solved urgently. Laser welding of AlSi10Mg alloys fabricated by selective laser melting (SLM) with an addition of Er and Zr in the filler metal was carried out. The effect of Er and Zr addition on the porosity, microstructures and mechanical properties of the welded joints was investigated, and the contribute of Er and Zr addition to the yield strength (YS) of the welded joints was calculated. Compared that joints without Er and Zr addition, the average ultimate tensile strength (UTS) and YS of the welded joints with Er and Zr addition have been increased by 10.5% and 23.5%, respectively. The improved mechanical poverty of the welded joints is due to the refined α-Al grains and Si-rich cellular networks, and the reduced hydrogen pores occurred in the weld metal (WM) with the addition of Er and Zr. The YS calculation of the weld joints indicates the most important contribution to the YS is the enhancement effect of the Si-rich networks with Er and Zr.