Journal of Magnesium and Alloys (Sep 2020)
Comparisons of microstructure homogeneity, texture and mechanical properties of AZ80 magnesium alloy fabricated by annular channel angular extrusion and backward extrusion
Abstract
This paper provided an efficient single pass severe plastic deformation (SPD) method, annular channel angular extrusion (ACAE), for fabricating AZ80 magnesium alloy shell part. The effect of ACAE process on the microstructure homogeneity, texture, and mechanical properties of extruded part was experimentally investigated. For comparison, conventional backward extrusion (BE) was also conducted on processing AZ80 part with same specification. The results showed that ACAE process has a better capacity to refine the microstructure and dramatic improve the deformation homogeneity of the extruded part than BE process. Due to two strong shear deformations were implemented, ACAE process could also concurrently modify the basal texture more notably than BE process. In particular, a bimodal texture was found in ACAE extruded part, which was greatly related to the enhanced synergetic action of basal slip and secondary slip caused by the effective shear stress. More uniform and superior hardness along the thickness and height of part were achieved via ACAE process. Further surveying of tensile tests also showed that the part fabricated by ACAE process exhibited significantly higher and far more homogeneous tensile properties with an excellent balance of strength and ductility. The remarkable enhanced tensile properties of ACAE extruded part could be primarily attributed to the significant grain refinement, which provided a powerful grain boundary strengthening effect and meaningfully suppressed the development of twin-sized cracks during tensile deformation. It was established that ACAE process seemed to be a very promising single pass SPD method for manufacturing Mg-based alloy shell parts with more homogeneous microstructure and superior performance.
