Simulation Analysis of the Extrusion Process for Complex Cross-Sectional Profiles of Ultra-High Strength Aluminum Alloy

Ultra-high-strength aluminum alloy profile is an ideal choice for aerospace structural materials due to its excellent specific strength and corrosion resistance. However, issues such as uneven metal flow, stress concentration, and forming defects are prone to occur during their extrusion. This study focuses on an Al-Zn-Mg-Cu ultra-high-strength aluminum alloy profile with a double-U, multi-cavity thin-walled structure. Firstly, hot compression experiments were conducted at temperatures of 350°C, 400°C, and 450°C, with strain rates of 0.01 and 1.0 s−1, to investigate the plastic deformation behavior of the material. Subsequently, a 3D coupled thermo-mechanical extrusion simulation model was established using Deform-3D to systematically analyze the influence of die structure and process parameters on metal flow velocity, effective stress/strain, and temperature distribution. The simulation revealed significant velocity differences, stress concentration, and uneven temperature distribution. Key parameters, including mesh density, extrusion ratio, die fillet, and bearing length, were optimized through full-factorial experiments. This optimization, combined with a stepped flow-guiding die design, effectively improved the metal flow pattern during extrusion. Trial production based on both the initial and optimized parameters were carried out. A comparative analysis demonstrates that the optimized scheme results in a final profile whose cross-section matches the target design closely, with complete filling of complex features and no obvious forming defects. This research provides a valuable reference for the extrusion process optimization and die design of complex-section profiles made from ultra-high-strength aluminum alloys.