A new way to analyze constitutive analysis and its relation to the microstructure of a Mg-Gd-Y-Zn alloy

It is the first time that we have systematically proved that the activation energy ( Q -value) is the main parameter that controls the dynamic recrystallization during hot deformation, and the reliability of the constitutive analysis is entirely dependent on the Q -value. To this end, the hot deformation behavior of a Mg-Gd-Y-Zn alloy was investigated at the temperatures of range 573 K-723 K under strain rates of range 0.0001–1 s ⁻¹. Subsequently, the Q-value ∼ 331.24 kJ mol ⁻¹ was achieved. By considering the two different approaches of eliminating the temperatures and then eliminating the strain rates, the lowest Q-values ∼ 259.75 kJ mol ⁻¹ and ∼ 295.80 kJ mol ⁻¹ were achieved, respectively. Based on the lowest Q-values, the deduced parameters of temperatures range of 623 K-723 K and strain rates range of 0.0001–0.01 s ⁻¹ were evaluated. Interestingly, the numerical simulation exhibited a further lower Q-value ∼ 237.17 kJ mol ⁻¹. The difference in the Q -values revealed that the large strain hardenability is due to the high Q-value, while the low strain hardenability is due to the low Q-value. The deduced parameters were also well-matched with the processing maps and the EBSD analysis. Last but not least, the deduced parameters displayed a high accuracy in predicting the flow stresses. Thus, the new approach is of great significance in analyzing the accurate calculation of Q-value, the correctness of constitutive analysis, and evaluating stress-strain behavior.