Investigation of microstructure and mechanical properties of Al-Si alloy thin walled cylindrical part fabricated by CMT based WAAM process

Wire Arc Additive Manufacturing (WAAM) represents a major advancement in the production of large-scale metal components. WAAM is recognized for its capacity to produce components with enhanced material properties and structural integrity compared to conventional manufacturing processes. As WAAM involves layer-by-layer fabrication, the resulting components exhibit a higher degree of anisotropy in microstructural and mechanical properties. Additionally, the properties of WAAM components can vary significantly in terms of microstructure and mechanical performance along the build direction of the multi-layered parts. This study investigates the mechanical and microstructural properties of thin-walled cylinder made from Al-Si (Al 4043) alloy using CMT-WAAM. The analysis aims to elucidate the factors contributing to variations in these properties and provide insights into the underlying reasons for observed discrepancies. The micro hardness, tensile strength, and impact strength are analysed at both bottom and top region of the thin walled cylinder. The microhardness, tensile strength, and impact strength of the bottom region are 14.51%, 3.14%, and 12.19% less than those of the top region, respectively, due to the repeated thermal cycles during subsequent layer deposition. Fractographic analysis indicates a ductile fracture mode, characterized by the presence of dimples and microvoid coalescence. Further, the microstructural analysis reveal that top region consists fine grain compared to bottom region of thin-walled cylinder. X-ray Diffraction (XRD) analysis identified secondary phase particles, such as MgSi2 and Al9Si, at the grain boundaries, which was further confirmed by EDS analysis. These microstructural changes and the presence of secondary phases are reasons for the changes in the mechanical properties along build direction.