Effect of Extrusion Ratio on the Microstructure and Mechanical Properties of Al-0.5Mg-0.4Si-0.1Cu Alloy

Al-0.5Mg-0.4Si-0.1Cu alloy possessing weather resistance and oxidation resistance can obtain good surface quality (metallic luster) without chrome plating. Therefore, it is an important material to replace polluting chrome-plated aluminum profiles for automotive decorative parts. At present, studies about the extrusion process of Al-0.5Mg-0.4Si-0.1Cu alloy are very few, which affects its further application. In this work, the effect of extrusion ratios on microstructure and mechanical properties of Al-0.5Mg-0.4Si-0.1Cu alloy is investigated by optical microscopy (OM), scanning electron microscopy (SEM), electron backscattered diffraction (EBSD), transmission electron microscopy (TEM) and tensile tests. The results showed that the dynamic recrystallization degree of the alloy gradually increased with the extrusion ratio increasing, which is attributed to the driving force provided by the large extrusion ratio. Meanwhile, due to the occurrence of dynamic recrystallization, the texture changed from <111> to <001> orientation. In addition, grains were obviously refined and uniform with the extrusion ratio increasing. Due to the fine grain strengthening mechanism, the tensile strength and elongation of the alloy with an extrusion ratio of 30 reached 152 MPa and 32.4%.