Study on structure homogeneity of plate sample with large dimension during equal channel angular pressing (ECAP)

摘要

A self-made die with large cross section (180.2 × 22.2 mm) for equal channel angular pressing (ECAP) was used to study the influence of two different pressing routes (C_X and C_Y) on refining homogeneity of high-purity aluminum plates. Microstructures were investigated by optical microscopy (OM) and electron back scatter diffraction (EBSD) methods, and micro-hardness and tensile tests were taken to evaluate deformation degree across the cross section and mechanical properties, respectively. The results indicate that pressing routes of ECAP have a great influence on structure homogeneity of plate samples. The route C_Y leads to fine grains with better homogeneity because the same deformation direction is taken through each pass. Coarse columnar crystals with 3-4 mm change to 68.6 μm nearly equiaxed grains and a strong cube texture forms after four C_Y passes, and corresponding mechanical properties increase by a factor compared to as-cast plate.