Investigating effect of recrystallization mechanism on deformation mode and texture evolution is conducive to controlling deformation mechanism and texture in magnesium alloys under medium-high temperature impact loading. In the present study, a Johnson-Cook model incorporating twin strengthening was established to simulate macro-deformation, and a twinning induced recrystallization (TDRX) model and bulging recrystallization (GBBDRX) model are introduced into visco-plastic self consistant (VPSC) framework to quantitatively study the deformation mechanism of pre-twinned AZ31 magnesium alloy during medium-high temperature impact loading. Both TDRX and GBBDRX occur, with basal slip as the dominant slip system, followed by pyramidal 〈c + a〉 slip and prismatic slip. The dynamic recrystallization (DRX) significantly influences basal and pyramidal 〈c + a〉 slip systems, with minimal impact on secondary deformation mechanism. In addition, the recrystallization mechanism of grain boundary bowing increases the activity of basal slip and decreases the activity of pyramidal 〈c + a〉 slip. The nucleation and growth of recrystallized grains enhance basal slip activity and suppress pyramidal 〈c + a〉 slip, leading to the formation of a strong basal texture. As dynamic recrystallization progresses, a bimodal texture develops, characterized by a reduction in basal component pole density and a more pronounced basal slip.

The damage anisotropy of an extruded ZK60 Mg alloy is characterized using tensile tests and scanning electronic microscopy. The accumulation of anisotropic deformations leads to the great differences of the dimple evolution and strains at fracture along different loading directions. To introduce the anisotropic deformation information into the damage constitutive relationship, a thermodynamically consistent phase-field model of ductile damage fully coupled with elastoplastic finite deformations is developed in this study. Using the user-defined constitutive relationship and displacement-temperature coupling element, the finite element simulations are conducted. The results show that: (1) ZK60 Mg alloys presents clear R-value difference in 0°, 45°, and 90° tests of intact specimens. The 45° test possesses the greatest R-value (1.50) and the greatest strain at fracture, however, the R-value for 0° is less than 1, indicating the thinning is preferential. (2) The higher ultimate stress leads to a larger average dimension of the dimples, whereas the higher density correlates with a larger elongation ratio at the fracture. The disappearance of the stress-bearing area indicates that the phase-field assumption on stress degradation is completely compatible with the dimple analysis on fractography. (3) The simulation results of the stress-strain relationships and damage paths correlate well with the experimental ductile damage of magnesium alloys at 200 ℃. Slight errors are basically attributed to the modeling parameters and finite element iteration algorithm. The proposed model presents fine applicability and reliability for the predictions of plastic deformations, ductile damage, and fracture of anisotropic Mg alloys.

In this study, a phase-field scheme that rigorously obeys conservation laws and irreversible thermodynamics is developed for modeling stress-corrosion coupled damage (SCCD). The coupling constitutive relationships of the deformation, phase-field damage, mass transfer, and electrostatic field are derived from the entropy inequality. The SCCD localization induced by secondary phases in Mg is numerically simulated using the implicit iterative algorithm of the self-defined finite elements. The quantitative evaluation of the SCCD of a C-ring is in good agreement with the experimental results. To capture the damage localization, a micro-galvanic corrosion domain is defined, and the buffering effect on charge migration is explored. Three cases are investigated to reveal the effect of localization on corrosion acceleration and provide guidance for the design for resistance to SCCD at the crystal scale.