Effect of temperature on the microstructure and mechanical properties of Mg-Gd-Y-Zn-Zr alloy during the large height-to-diameter ratio upsetting and extrusion

Abstract

In this paper, the Mg-9Gd-4Y-2Zn-Zr (wt. %) alloy was used as the research object. The effect of deformation temperature on the microstructure and mechanical properties of the alloy after one pass of large height-to-diameter ratio (5.5) upsetting and extrusion was studied. The microstructure evolution of one pass large height-to-diameter ratio upsetting and extrusion process was studied, which provided a theoretical basis for further study of large height-to-diameter ratio reciprocating upsetting and extrusion. The results show that with the increase of deformation temperature, the grain size decreases, the dynamic recrystallization rate increases, the granular β phase increases, the texture of the alloy tends to the typical extrusion texture, and the texture intensity increases gradually. With the increase in temperature, the mechanical properties of the alloy after upsetting and extrusion with a large height-to-diameter ratio increase. The ultimate tensile strength (UTS) of the alloy deformed at 460 °C increased to 355 ± 6.7 MPa, the yield strength (YS) increased to 139 ± 3.1 MPa, and the elongation (EL) was 17 ± 0.7%. In the process of upsetting extrusion with the large height-to-diameter ratio, the initial discontinuous dynamic recrystallization (DDRX) changes to continuous dynamic recrystallization (CDRX).