Analysis and Characterization on Dynamic Recrystallization in Casting AZ31 Mg Alloys Under Plane Strain Compression

Abstract

Studies on twinning, twin-induced dynamic recrystallization (TDRX), and their temperature and strain rate dependences are of considerable significance to the ultimate strength and plastic formability of the coarse-grained Mg alloys during severe plastic deformation. Plane strain compression tests were conducted on the parallelepiped samples of casting AZ31 Mg alloys. The twinning and recrystallization behaviors close to and away from the crack boundaries were characterized using electron backscatter diffraction. The results show: (1) with increasing strain rate for tests, the extension twin proliferates significantly. Due to the local stress concentration, the TDRX is more active in the area close to the crack tip and exhibits the positive strain-rate sensitivity as twinning; (2) the TDRX is not only stress-favored but also closely links to the temperature. However, the TDRX is not utterly proportional to the temperature. Compared to 400 °C, 300 °C is more beneficial to the TDRX, achieving the higher strength and plastic deformability. The main reason is that the higher strain-hardening rate and flow stress at the higher strain rate and lower temperature motivates the transformation from twinning to the fine twin-walled grains more efficiently, and the stress-favored TDRX is crucial to refine grains and continue plastic deformation for the casting Mg alloys with coarse grains.

Interactions between twins and dislocations in ZK60 alloy under dynamic compression

“…This result is attributed to the fact that the strain rate influences the hardening effect of twins and the softening effect of twin-induced dynamic recrystallisation. This is similar to the results provided by Xu et al [12]. In addition to the high strain rate research on as-cast Mg alloys, wrought Mg alloys have also been extensively studied due to their fine texture and better comprehensive mechanical properties.…”

Qualitative and Quantitative Investigations on the Failure Effect of Critical Fissures in Rock Specimens under Plane Strain Compression

“…The changing stress on a laterally confined device is associated with the lithology and fracture process of rock samples. Currently, PSC tests are most common in geotechnical contexts [ 3 , 4 , 5 ] and other investigations for metallic material properties [ 6 , 7 , 8 ], and there have been few PSC test studies for rock materials. Relevant studies involve the validation of rock PSC test benches, the observation of rock strain localization in simulation tests [ 9 , 10 ], and the analysis of the fracture mechanics of rock-like materials [ 11 , 12 ].…”