The effect of multi-pass ECAP on the microstructure and properties of 6xxx aluminum alloys at different temperatures

The 6xxx series (Al-Mg-Si) aluminum alloys are widely used in automotive, aerospace, and construction areas due to their high strength, good corrosion resistance, and excellent extrudability. In this paper, the optimization of the equal channel angular pressing (ECAP) was studied by processing Al-1Mg-1Si-0.5Mn-0.5Cu-0.1Sc sample with ECAP and examines the effects of ECAP passes and temperature on the microstructure and mechanical properties. The microstructures were observed by using optical microscopy and scanning electron microscopy (SEM). The result indicates that after six passes of ECAP at 150°C, a high yield strength and tensile strength were tested, which were respectively 260.16 MPa and 270.14 MPa. After four passes at 200°C, the highest elongation was tested, reaching 12.75%. The grains undergo a significant deformation during the ECAP process, with a noticeable reduction in size. At higher temperatures, grain coarsening occurs. The morphology of the second-phase particles would change with the number of ECAP passes increasing, and the texture formed during the extrusion process would evolve with the accumulating of strain.