Effect of complexity design on the physical-mechanical properties of extrusion welded aluminum panel

• Complex aluminum panel designs result in finer grain structures due to higher deformation and strain during material flow but exhibit inferior mechanical properties, such as lower hardness, tensile strength, and bending strength, compared to simpler designs. • Complex aluminum panel design is attributed to divided material flow, random grain orientations, and uneven quenching. • Optimizing panel profile designs and post-extrusion processes is crucial to balancing the complexity of panel shapes with their mechanical performance, ensuring effective integration of structural and mechanical requirements. The transportation sector, particularly high-speed trains and Light Rail Transit (LRT), has a high demand for extruded aluminum alloy panels. These panels often require tens of meters in length, but production limitations prevent manufacturers from producing such lengths in a single extrusion. As a result, joining techniques are essential. However, traditional welding methods primarily bond the outer skin without effectively joining the internal fins, resulting in weaker structures. To address this limitation, extrusion welding using a porthole die and welding chamber is proposed as a superior alternative. The design of aluminum panel profiles varies based on application, ranging from simple to complex shapes. Design complexity is influenced by factors such as fin shape, thickness, and slope. Macrostructural and microstructural analyses indicate that as panel designs become more complex, grain structures become finer, driven by increased deformation and strain during material flow through the mold. Mechanical testing further reveals that panels with simpler designs exhibit higher hardness, tensile strength, and bending strength compared to more complex designs. This difference is attributed to the divided material flow in complex molds, which causes higher strain levels and results in random grain orientations. Additionally, panels with highly complex designs experience uneven cold air quenching after extrusion, leading to less homogeneous microstructures and precipitate distributions. Consequently, the mechanical properties of panels with complex designs are inferior to those of simpler designs. These findings underscore the importance of optimizing panel profile designs and post-extrusion processes to balance complexity and mechanical performance effectively.