Improvement of mechanical properties of AL (A356) cast alloy processed by ECAP with different heat treatments

Severe plastic deformation (SPD) by equal channel angular pressing (ECAP) has been used as a reliable method to achieve an ultra-fine and homogenous microstructure in the bulk materials. In this research, study was conducted on the structures and mechanical properties of A356 (7%Si) Al alloy produced by severe plastic deformation through ECAP. Special attention was paid to the effect of heat-treatments such as annealing, solution, quenching and pre/post-aging on the properties of the materials. The heat treated as cast structure was successfully deformed in ECAP process. The yield strength, ultimate strength, and hardness of the ECAP samples were improved after pre/post-artificial aging. Mechanical properties improvement was achieved after ECAP process in the samples with the pre-aging treatment. The results show near 114% improvement of the ultimate tensile strength (UTS) and 166% elongation from the as-cast structure. From experimental work, it was also found that the acceleration of precipitation kinetics after ECAP process is not important factor to achieve improvement of mechanical properties, but distribution of Si particles with precipitates formed during T6 is important in high UTS achievement along with high elongation.