The influences of extrusion-shear process on microstructures evolution and mechanical properties of AZ31 magnesium alloy

Abstract

Severe plastic deformation (SPD) technologies are difficult to be promoted to be industrialized, and the processes are complicated, and the costs are high. To promote industrial application of the SPD technology for magnesium alloy, a new successive SPD method has been explored which includes direct extrusion and two steps equal channel angular extrusion (ECAE) continuously. The processing technology is called extrusion-shear (ES) in this paper. The components of ES dies have been designed, manufactured and installed on extruder to manufacture the AZ31 magnesium alloy rods. Microstructures of AZ31 magnesium alloy processed by ES process have been observed and investigated. The texture evolution during ES process has also been studied. The results show that fine and uniform microstructures can be obtained by ES process. Basal texture (0002) has been weakened owing to shear deformation of ES process. Research results show that relationship between grain sizes and hardnesses is consistent with hall-petch law at 420 °C. ES process with low billet temperature could improve hardness obviously and enhance compression performance, and raise strengths. And there exits strong tension-compression asymmetry of AZ31 magnesium alloy fabricated by ES process. The results indicate that ES process can produce large plastic deformation and introduce ultra-fined grains in the AZ31 magnesium alloy.