剪切角对AZ31镁合金双峰晶粒尺寸和压缩性能的影响

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

摘要:

采用挤压剪切(ES)工艺制备了AZ31棒材，其剪切角分别为150°、135°和120°。采用ES法制备了AZ31镁合金。用光学显微镜、扫描电镜和电子背散射衍射等手段研究了AZ 31合金双峰晶粒的显微组织演变。研究结果表明，大粒面积所占的比例随应变的增加而增加。从OM图像中可以看到双峰状的晶粒结构，窄的粗晶粒被细小的晶粒包围。织构随ES过程的不同剪切角而发生变化。屈服强度和峰值强度都随着剪切角的减小而逐渐增大。随着剪切应变的增加，随着剪切角的减小，大晶粒的比例增大，小晶粒的尺寸增大，这是因为变形和动态再结晶分数都随着剪切角的减小而增大。

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.