Effect of thermo-mechanical processing parameters on the dynamic restoration mechanism in an Mg-4Y-2Nd-1Sm-0.5Zr alloy during hot compression. (10th November 2021)

• Record Type: Journal Article
• Authors: Gui, Yunwei; Ouyang, Lingxiao; Xue, Yibei; Li, Quanan
• Is Part Of: Journal of materials science & technology. Volume 90(2022)
• Page Start: 205
• Page End: 224
• Publication Date: 2021-11-10
• Subjects: Mg-RE alloy -- TMP parameters -- Processing map prediction -- Constitutive analysis -- Dynamic restoration mechanism; Metals -- Periodicals; Materials science -- Periodicals; Materials science; Metals; Periodicals; 620.1105
• DOI: 10.1016/j.jmst.2021.02.036
• Languages: English
• ISSNs: 1005-0302

Abstract

Highlights: The constitutive equation of the Mg-RE alloy is developed, and the processing map is also constructed to predict the optimum TMP parameters. Stress components and apparent activation energies for each TMP parameter calculated through the constitutive equation reveal which type of the DRX is dominated. At the high temperature and low strain rate, more DDRX characteristics occurs at the beginning and then the DDRX + CDRX synergistic effect. The DDRX + CDRX synergistic effect occur throughout the whole process at high temperature and high strain rate. Deformation twins have occurred and provided nucleation sites for DRX grains at low temperature and low strain rate. Abstract: Microstructure evolution and dynamic restoration mechanism of solution-treated Mg-4Y-2Nd-1Sm-0.5Zr alloy have been studied under three TMP parameters consisting of deformation temperatures (350–500 °C), strain rates (0.01–5 s −1 ), and strains (0.2, 0.4, and 0.8). A strong dynamic softening is observed in all stress-strain curves, even at higher strain rates (1 and 5 s −1 ) due to an adiabatic heating effect. Various stress-strain curves are applied to construct a processing map and develop an Arrhenius-type constitutive equation. With the prediction of the processing map, an optimal processing domain has been determined to be the temperature range 450–500 °C and strain rate range 0.01–0.1 s −1 at a strain of 0.8. The volume fraction of DRX grains is the largest in the corresponding domain of high temperature and low strain rate. For the effect of TMP parameters on the dynamic restoration, the discontinuous dynamic recrystallization (DDRX) and continuous DRX (CDRX) synergistic effect occur throughout the whole process at high temperature and high strain rate. In terms of high temperature and low strain rate, DDRX characteristics at a low strain and then the DDRX + CDRX synergistic effect is observed at a higher strain. Although the DRX process is weak at low temperature and low strain rate, deformation twins have occurred and provided nucleation sites for DRX grains. Graphical abstract: Image, graphical abstract