The influences of shear angles on the bimodal grain sizesand compression properties of AZ31 Mg alloy

Abstract:

AZ31 rods have been prepared by the extrusion-shear (ES) process with different shear angles 150°, 135° and 120°. The commercial AZ31 magnesium alloy was prepared by ES process which includes direct extrusion process and subsequent shearing process.Microstructures evolution of AZ31 alloys with bimodal grains have been investigated by using optical microscopy, scanning electron microscopy and electron backscattered diffraction. The research results showed that proportion of the large grain area increases with rising of strains. From the OM images it can be seen bimodal grained structures, and the narrow coarse grains are surrounded by the fine grains.the texture changes with different shear angles of the ES process from the pole figures.Both the yield strengthes and the peak strengthes increase with decrease of the shear angles gradually.As the shear strains increases, the proportion of large grains increases while the size of small grains increases because both the deformation and the dynamic recrystallization fraction increase with the decreases of shear angles.