Effects of solution temperature on microstructure and mechanical properties of Al-Si-Mg aluminum alloy fabricated by wire-arc additive manufacturing

Al-Si-Mg aluminum alloys exhibit excellent machinability as heat-treatable strengthened aluminum alloys. Heat treatment has a great influence on the microstructure and mechanical properties of Al-Si-Mg aluminum alloys. In this study, the ZL114A aluminum alloy wire was used to fabricate the Al-Si-Mg thin-walled component based on the wire-arc additive manufacturing process of metal inert-gas welding. The microstructure and mechanical properties of the ZL114A aluminum alloy components were investigated in both the as-deposited and heat treated at different solution temperatures. The results indicated that the microstructure of as-deposited ZL114A aluminum alloys consisted mainly of dendrites. The dendritic morphology disappeared after solid solution treatment (ST) at different temperatures, and the eutectic Si phase appeared coarsened and spheroidized. Numerous β″ phases were observed to have precipitated within the grains by transmission electron microscopy. The tensile properties of the alloy were improved due to precipitation strengthening of the β″ phase and spheroidization of the eutectic silicon phase. After the solid ST at 540 °C for 9 h and artificial aging treatment at 170 °C for 8 h, the yield strength and ultimate tensile strength of the alloy reached the maximum values of 344 and 377 MPa, respectively.