Improvement of microstructure and fatigue performance of wire-arc additive manufacture d 4043 aluminum alloy assiste d by interlayer friction stir processing

To expand the application of wire-arc additive manufacturing (WAAM) in aluminum alloy forming com-ponents, it is vitally important to reduce the porosity, refine microstructure, and thereby improve the mechanical properties of the components. In this study, the interlayer friction stir processing (FSP) tech-nique was employed to assist the WAAM of 4043 Al-Si alloy, and the related effects on the microstructure evolutions and mechanical properties of the fabricated builds were systematacially investigated. As compared to the conventional WAAM processing of Al-Si alloy, it was found that the introduction of in-terlayer FSP can effectively eliminate the pores, and both the alpha-Al dendrites and Si-rich eutectic network were severely broken up, leading to a remarkable enhancement in ductility and fatigue performance. The average yield strength (YS) and ultimate tensile strength (UTS) of the Al-based components produced by the combination of WAAM and interlayer FSP methods were 88 and 148 MPa, respectively. Meanwhile, the elongation (EL) of 37.5% and 28.8% can be achieved in the horizontal and vertical directions, respec-tively. Such anisotropy of EL was attributed to the inhomogeneous microstructure in the stir zone (SZ). Notably, the stress concentration can be effectively reduced by the elimination of porosity and Si-rich eu-tectic network fragmentation by the interlayer FSP, and thus the fatigue behavior was improved with the fatigue strength and elongation increased by similar to 28% and similar to 108.7%, respectively. It is anticipated that this study will provide a powerful strategy and theoretical guidance for the WAAM fabrication of Al-based alloy components with high ductility and fatigue performance. (C) 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.