Improvement in cold formability of AZ31 magnesium alloy sheets processed by equal channel angular pressing

Abstract

The microstructure, texture development and mechanical properties of AZ31 magnesium alloy sheets processed by equal channel angular pressing (ECAP) were investigated in this work. The results were correlated with the forming behavior at room temperature after single ECAP pass at different processing temperatures. A novel tool was developed for the implementation of ECAP to deform sheets with dimension of 200×200×1.8mm3. ECAP trials were carried out successfully at three temperatures of 175, 200 and 225°C using a channel angle of 130°. After the ECAP process, significant grain refinement and texture changes occurred in the AZ31 sheets. In particular, dynamic recrystallization was observed in the ECAPed sheets at 225°C. The tensile tests at room temperature showed that uniform elongation along the pressing direction (PD) increased with increasing processing temperature. The highest uniform strain at room temperature was 17.6% in the ECAPed sheet at 225°C. Forming tests of a U-channel section at room temperature revealed that the drawing depth of the ECAPed sheet at 225°C was improved by more than 50% as compared with the as-rolled condition.