Hot deformation behavior of extruded Mg-Zn-Y-Zr alloy

The Mg-Zn-Y-Zr alloys, which exhibit high strength and high elongation, have great potential for applications in many fields, such as automotive, aircraft, and aerospace industries. However, plastic deformation behavior under hot compression is still not fully understood. Hot compression tests of extruded Mg-Zn-Y-Zr alloy were performed at temperatures from 250 °C to 450 °C and strain rates from 0.001 s−1 to 1 s−1. A constitutive equation and processing map were developed to describe the flow characteristics. In addition, isothermal forging tests were conducted to verify the optimal deformation parameters. The results show that the strain rate and deformation temperature exert remarkable influences on the flow stress. The average activation energy and the stress exponent of deformation were determined as 137.400 kJ/mol and 3.707, respectively. The efficiency of power dissipation was high for all deformation conditions compared to the cast Mg-Zn-Y-Zr alloy, and the processing map exhibited four domains with high efficiency of power dissipation. The optimal deformation temperatures and strain rates for extruded Mg-Zn-Y-Zr alloy were 350-400 °C and 0.001-0.1 s−1, respectively. Components were prepared successfully according to the optimal deformation temperature and strain rate, which exhibited good surface quality and no deformation defect. The component after aging treatment exhibited an ultimate tensile strength of 396 MPa, a yield strength of 356 MPa and an elongation of 5.2%.