Investigation of microstructure and mechanical properties of Al (A356) after processing by ECAP and its simulation

Equal channel angular pressing (ECAP) is one of the important methods of severe plastic deformation for the fabrication of ultrafine-grained metals and alloys. The aim of this research is to study the improvement and amendment of the microstructure and mechanical properties of aluminum alloy (A356) by ECAP, which is having vast application in air-space industries. A die with channel contiguity angel of 120 and outer arc of curvature of 20 degrees were fabricated. Furthermore, the samples were annealed and the solution treatment was performed before the beginning of the process. Hardness, compression and tensile tests were applied on samples after the process was performed and microstructures of samples were evaluated by means of optical microscopy before and after the process. Mechanical properties of samples were studied and fracture surfaces of samples were characterized using scanning electron microscope (SEM). The results showed that hardness of the annealed sample was increased from 48 to 84.2 Vickers after 2 passes of ECAP and the results of the tensile test showed that the tensile strength was increased from 57 to 177 M.pa after 1 pass of ECAP. Finite element simulation method was applied on the aluminum alloy (A356) to estimate the variation of stress and strain distribution on the samples. The observation indicated that, the highest level of strain occurred on the center portions of samples and 0.25 percent error was detected from the theory state. Comparing the yield stress with simulation method indicated only 3.7 percent error.