Effect of severe plastic deformation on tensile properties of a cast Al–11 mass% Si alloy

Abstract

Up to now, investigations for the effect of the severe plastic deformation on mechanical properties of the processed materials are not enough. In the present work, tensile properties of a cast Al–11 mass% Si alloy processed by rotary-die equal-channel angular pressing (RD-ECAP) with 4–32 passes were investigated at room temperature. Elongation to failure significantly increased with the number of RD-ECAP passes from 4 to 32. For example, the sample pressed 32 passes has 10 times higher elongation (∼15%) than the as-cast alloy (∼1.5%). These results show that the cast Al–11 mass% Si alloy was transformed into a ductile alloy by RD-ECAP. Yield strength was noticeably improved by first four passes of RD-ECAP (about 40%) compared with that of the as-cast alloy. Fine-grained microstructure of the aluminum alloy matrix (about 300 nm) and modified grain boundaries after RD-ECAP is the primary reason for exhibiting significant ductility of this alloy. Grain boundary sliding (GBS) occurred at the room temperature tensile testing in the RD-ECAPed sample. The plastic deformation and fracture mechanism of the cast Al–11 mass% Si alloy were markedly changed by RD-ECAP.