Effect of Al-Mg Filler Wires on Weldability of Cold Metal Transfer Welded AlSi10Mg Alloys Fabricated Using Laser Powder Bed Fusion

Cold Metal Transfer (CMT) welding was performed on laser powder bed fusion (L-PBF) AlSi10Mg alloys using ER5183 and ER5356 Al-Mg filler wires. The effects of the ER5183 wire on the porosity, microstructure, and mechanical properties of the welded joints and weld metal (WM) were compared with those of the ER5356 wire. The results show that the porosity and pore size in the WM produced with the ER5183 wire are reduced relative to those in the WM produced with the ER5356 wire. The ultimate tensile strength (UTS) of the welded joints made with ER5183 and ER5356 wires is 224.5 and 222.6 MPa, respectively, reflecting a similarly reduced UTS compared to the base metal (BM). Fractures in the welded joints occur in the non-dendritic equiaxed zone (EQZ), which may be attributed to the enhanced heterogeneous nucleation of Al3Ti particles, facilitated by the increased Ti content from both the BM and the filler wires. Additionally, the WM, excluding the EQZ, shows UTS values of 267.6 and 238.4 MPa for the ER5183 and ER5356 wires, respectively. These findings suggest that the WM produced with ER5183 wire exhibits a significantly higher UTS compared to that produced with ER5356 wire. This enhancement can be attributed to factors such as increased solid solution strengthening, grain boundary strengthening, texture strengthening, the presence of nanosized Si precipitates and Si network boundaries, and the load transfer effects of the Si-rich networks. Moreover, the UTS of the WM with the ER5183 wire is 19.2 pct higher than that of the corresponding welded joint.