Effect of Copper on Extrudability of High-Strength AA6082 Aluminum Alloys

<div>There is a critical need to understand and optimize the extrudability of AA6xxx alloys, which are widely used in industries such as automotive and aerospace due to their favorable combination of strength, formability, and corrosion resistance. Surface cracking during the extrusion process remains a significant challenge, compromising the material’s mechanical properties and product quality. While previous studies have investigated surface cracking using various techniques, the underlying mechanisms remain elusive, especially regarding the role of important alloying elements such as copper. Therefore, this research provides a thorough investigation of the effect of copper additions on the solidus temperature, hot deformation behavior, and extrudability of AA6xxx alloys. Using experimental and numerical methods, the material’s solidus temperature and constitutive behavior were determined. Extrusion trials were conducted for alloys with different copper levels using a flat die over a range of extrusion speeds, with the resulting surface defects being examined. The findings indicate that although the copper content had little impact on the hot compression behavior, it did affect the solidus temperature. Alloys with a higher level of copper had a lower solidus temperature, and hence, the maximum extrusion speed for a given temperature was lower. Numerical simulations demonstrated that surface cracking occurred once the surface temperature of the alloy reached 96% of the solidus temperature. This study contributes to the optimization of extrusion processing by highlighting the role of copper in improving the extrudability of high-strength AA6xxx aluminum alloys, offering insights for developing higher-quality alloy products.</div>