Microstructural and Mechanical characterization of Overhanging AA 4043 structures fabricated by CMT Pulse based WAAM for Automotive applications

This study investigates the fabrication and characterization of overhanging structures using the Cold Metal Transfer (CMT) pulse based Wire Arc Additive Manufacturing (WAAM) technique, specifically targeting automotive applications on commercial aluminum components. Focusing on optimal welding strategies for overhanging structures, components are fabricated by providing offsets during consecutive deposition of layers, thus producing parts with angles of 45, 60 and 90 degree inclinations from the substrate. Three specimens undergo twenty-three layers of deposition, resulting in structurally sound joints within this specified angle range. AA 4043 electrode is utilized, and welding parameters are optimized through trials by verifying with bead on plate deposition. Successful outcomes are achieved within the specified angle range, though challenges arise beyond 60 degrees, complicating the maintenance of desired weld quality. The study further evaluates the microstructure, microhardness, and tensile properties of aluminum alloy (AA 4043) samples fabricated at different build orientations (90°, 45°, and 60°). Microhardness measurements indicate that the 60° orientation exhibits the highest hardness values across all positions, suggesting superior material strength and consistency. Tensile tests reveal that specimens fabricated at a 60° build orientation demonstrate the highest Ultimate Tensile Strength (UTS) of 217 MPa and a total elongation of 23.6%, indicating optimal mechanical performance. Microstructural analysis supports these findings, showing refined grain structures and uniform phase distribution in the 60° orientation compared to the rest. Conversely, samples at a 90° build orientation display inferior mechanical properties, with the lowest UTS (122 MPa) and total elongation (17.0%). This study also provides a foundational understanding of the importance of optimal welding strategies and orientations in the CMT pulse based WAAM process for overhanging structures, emphasizing its relevance for automotive applications for its potential in producing complex, high-performance aluminum structures suitable for automotive components.