Influence of heat treatment on the microstructure and mechanical properties of Al–Mg–Si alloy fabricated by double wires + arc additive manufacturing

Al-3.4Mg-1.7Si alloy single-pass and multi-layer thin wall components were fabricated with double wires + arc additive manufacturing procedure. Heat treatment was performed to further process the component. The microstructure and mechanical properties of the as-deposited and heat-treated components were comparatively investigated. After heat treatment, the grains grow up slightly, and the phase particles change to distribute semi-continuously, and a large number of nanoscale monoclinic β″ precipitated phases generate. The porosity increases to 0.0486% from as-deposited 0.0348%. The microhardness, ultimate tensile strength and yield strength are respectively improved by 25%,79%, and 228% with heat treatment process, with the hardness uniformity and elongation decreased.