Hybrid in-situ hot rolling and wire arc additive manufacturing of Al-Si alloy: Microstructure, mechanical properties and strengthening mechanism

Al-Si alloys are extensively utilized in aerospace and automotive industries owing to their exceptional wear and corrosion resistance. However, the traditional casting and the single wire arc additive manufacturing (WAAM) processes often lead to the formation of numerous pores and columnar grains within the material. In this study, a novel hybrid in-situ hot rolling and wire arc additive manufacturing (HR-WAAM) technique was employed to fabricate the Al-Si alloy, followed by a comprehensive analysis of its microstructure, mechanical properties, and strengthening mechanisms. The findings reveal that in-situ hot rolling enhances dislocation density within the aluminum matrix, promotes Si phase precipitation, and inhibits columnar grain growth. Moreover, it reduces deposition layer height and shortens pore overflow distance significantly, thereby effectively reducing porosity in the alloy. Notably, HR-WAAM samples exhibit an average ultimate tensile strength (UTS) of 156.0 MPa, a yield strength (YS) of 65.5 MPa, and an elongation (EL) of 16.2 %, corresponding to improvements of 13.0 %, 37.9%, and 29.6 % respectively compared to WAAM samples. This study is expected to provide a cost-effective and highperformance additive manufacturing approach for various aluminum alloys.