Mechanical behaviour and texture of annealed AZ31 Mg alloy deformed by ECAP

Abstract

AZ31 Mg alloy samples were processed by equal channel angular pressing (ECAP) at 220°C for four passes. An average grain size of ∼1·9 μm with reasonable homogeneity was obtained. The ECAP process imparted large plastic shear strains and strong deformation textures to the material. Subsequent annealing of the equal channel angular pressed samples produced interesting mechanical behaviours. While yield strength increased and ductility decreased immediately after undergoing ECAP, annealing at temperatures <250°C restored ductility significantly at a small decrease in of yield strength. Annealing at temperatures >250°C reduced yield strength without additional improvement in ductility. It is believed that the combination of stress relief via dislocation elimination, refined microstructure and the retention of a strong ECAP texture at low annealing temperatures enhance ductility. High temperature annealing breaks down the ECAP texture resulting in no further improvement in ductility. The results show that the mechanical properties of the alloy can be positively influenced by annealing after ECAP to achieve a combination of strength and ductility.

Thermal Stability and Mechanical Properties of Extruded Mg-Zn-Y Alloys with a Long-Period Stacking Order Phase and Plastic Deformation

“…The mean grain size of the α-Mg phase was about 10 µm, and the size of the inclusions of Mg 3 Zn 3 Y 2 compound was 1.7 µm. Fine-grained AZ31 Mg alloy annealed at 773 K for 1 h has a yield stress of 50 MPa, a mean grain size as large as 20 µm, and an improved elongation of 15% [13]. The alloy investigated in the present study showed even better mechanical properties.…”

Effect of the electropulsing on mechanical properties and microstructure of an ECAPed AZ31 Mg alloy

“…3,7,8 However, cracking occurred more easily at low temperature 8 and was also generated more easily with the increase in the number of passes, owing to the increment of the strain density in proportion to the number of passes. After treatment by traditional annealing, the elongation-tofailure of the ECAP-treated Mg alloys was almost the same or increased greatly; however, the strength decreased under the different conditions, 5,6,8 which may be attributed to the grain growth that occurred during conventional annealing. After treatment by traditional annealing, the elongation-tofailure of the ECAP-treated Mg alloys was almost the same or increased greatly; however, the strength decreased under the different conditions, 5,6,8 which may be attributed to the grain growth that occurred during conventional annealing.…”

“…[2][3][4][5][6][7] Evidently, either the strength or the ductility was increased after ECAP processing under different treatment parameters. [2][3][4][5][6][7] Evidently, either the strength or the ductility was increased after ECAP processing under different treatment parameters.…”

Recrystallization and microstructure evolution of the rolled Mg–3Al–1Zn alloy strips under electropulsing treatment

“…To solve this problem, as one of the most efficient methods for improving both strength and plasticity of metal materials, grain refinement has been widely applied to Mg alloys [3,4]. A process consists of plastic deformation and recrystallization is commonly used to achieve a favorable grain size [5][6][7]. Nevertheless, the conventional heat treatment which is often used to obtain recrystallized microstructure will accelerate the growth of recrystallization grains due to the relatively high annealing temperature and hence the strength and ductility of the material will be decreased.…”