Microstructure evolution and ductility improvement mechanisms of magnesium alloy in interactive alternating forward extrusion
(1. School of Materials Science and Chemical Engineering, Harbin University of Science and Technology, Harbin 150040, China;
2. Key Laboratory of Advanced Manufacturing and Intelligent Technology, Ministry of Education, Harbin University of Science and Technology, Harbin 150080, China)
2. Key Laboratory of Advanced Manufacturing and Intelligent Technology, Ministry of Education, Harbin University of Science and Technology, Harbin 150080, China)
Abstract: The microstructural evolution and mechanical properties of AZ31 magnesium alloy processed by the interactive alternating forward extrusion at different loading displacements (h=3, 6, 9 mm) were investigated. Optical microscopy (OM) and electron backscatter diffraction (EBSD) were used to analyze the evolution of microstructure, and the mechanical behavior was clarified by tensile tests and scanning electron microscopy (SEM). The results show that continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX) can achieve grain refinement jointly in interactive alternating forward extrusion. With the decrease of the loading displacement h, the proportion of recrystallization increases from 23.4% to 66.7%. The fiber texture gradually tilts to the extrusion direction (ED), and the grain orientation randomization of DDRX further weakens the fiber texture intensity. When h=3 mm, the ultimate tensile strength (UTS) is 249.1 MPa and the elongation can reach 29.4%.
Key words: magnesium alloy; alternating extrusion; grain refinement; texture weakening