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• Texture control achieved through pre-twinning followed by heat treatment (HT) positively influences room temperature (RT) stretch formability in AZX311 Mg alloys. • Pre-strained (PS) samples exhibit reduced formability, largely due to the predominance of pre-straining effects over the twin-induced texture. • HT at 250°C does not significantly modify the twin structure, thereby failing to counteract the detrimental effects of pre-stretching. • HT at 350°C and 400°C markedly improves IE values, though this occurs at the expense of the twin structure. • Enhanced RT formability results from the synergistic effects of coarser grains, a recrystallized microstructure, and the development of off-basal texture. In this study, the effects of pre-strain-induced tensile twins (TTWs) and controlled heat treatment on the formability behavior of AZX311 Mg alloy sheets were investigated. A 4% compressive strain was applied to pre-strain the sheets using the in-plane compression (IPC) technique along the rolling direction (RD) to introduce TTWs. The pre-strained (PS) samples were subsequently heat-treated at 250 °C, 350 °C, and 400 °C independently for 1 hr, and are termed as PSA1, PSA2, and PSA3, respectively. Erichsen cupping tests were conducted to assess the formability of the sheet samples under different initial conditions. The results showed that the PS sample heat-treated at 250 °C for 1hr exhibited a decrease in the Erichsen index (IE) compared to the as-rolled sample, whereas PSA2 and PSA3 samples showed an increase in IE values. Microtexture analysis revealed that most of the TTWs generated through pre-twinning were stable at 250 °C; however, the twin volume fraction reduced to 41% at 350 °C compared to the PS samples due to enhanced thermal activity at that temperature. Furthermore, PSA2 samples showed severe grain coarsening in some areas of the sample, and the fraction of such grains increased in the PSA3 samples. The stretch formability (IE value) of PSA2 samples showed a 32.3% increase compared to the as-rolled specimens. Additionally, the analysis of the deformed specimen at failure under the Erichsen test indicated that considerable detwinning occurs in the PS and PSA1 samples, whereas dislocation slip activity dominates in the PSA2 and PSA3 samples during stretch forming. Apart from detwinning and dislocation slip, deformation twins were also observed in all samples after the Erichsen test. Thus, this work highlights the importance of texture control and its underlying mechanisms via pre-twinning followed by heat treatment and their impact on the room temperature (RT) stretch formability of AZX311 Mg alloy sheets. [ABSTRACT FROM AUTHOR]

• Simple shear deformation and subsequent annealing exhibit larger fracture elongations regardless of direction. • A prismatic slip along with tension twinning and basal slip make considerable contributions to strain accommodation. • Shear zone shape and geometry influences strain homogeneity. • Simple shear deformation has been shown to alter the texture in Mg alloys. Sheet-metal products are integral parts of engineering industries and academia research. Various testing techniques have revealed the deformation behaviors of sheet metals under complex stress states. Information obtained from tensile and compression tests, however, are insufficient for the identification of material parameters relevant to modern constitutive laws, which require experimental setups capable of generating various loading conditions and applying great amounts of strain to sheet metals. In-plane shear testing has emerged as an important method to overcome the challenges associated with tension and compression tests and can provide additional information about deformation behaviors under large plastic strains. Materials such as Mg alloys with poor levels of both ductility and formability cannot accommodate large plastic strains. Therefore, tension and compression tests have limitations in explaining the material behaviors that occur during sheet metal forming where large plastic strains are introduced. Many studies have been conducted to explain the deformation behaviors of Mg alloys under shear deformation techniques. These include severe plastic deformation (SPD), especially the equal channel angular pressing (ECAP) and equal channel angular extrusion, rolling combined with shear deformation i.e. differential speed rolling (DSR), and also in-plane shear for sheet metals, particularly under large levels of plastic strain. These in-plane shear technique involves the Miyauchi shear test, ASTM shear test, and twin bridge shear tests. Moreover, many experimental results have revealed that the evolution of microstructure and texture during in-plane shear is closely related to the failure behavior of materials. Therefore, this review is focused on techniques for in-plane shear testing that have been reported thus far, on the effect of in-plane shear on the microstructure development of Mg alloy sheets, and on the usefulness of in-plane shear testing to evaluate the formability of Mg alloy sheets. [ABSTRACT FROM AUTHOR]

Micromechanical deformation behaviors of E-form fine grain (EFG), E-form coarse grain (ECG), and AZ31 magnesium (Mg) alloys were investigated and compared using a mini-V-bending test. EFG and ECG Mg alloys with a weaker texture showed better bendability compared with AZ31 alloy that has a stronger texture. The evolution of the microstructure and microtexture during the mini-V-bending process was experimentally analyzed via an electron back-scattered diffraction (EBSD) technique. This study was focused on the effect that deformation twinning exerts on the strain localization and crack initiation. The twin bands (TBs) developed in the tension zone of bent specimens found to be closely related to the strain localization and crack initiation during the mini-V-bending process. A resolved shear stress (RSS) criterion and microstructure based crystal plasticity finite element method (CPFEM) were used to theoretically predict the activation of { 10 1 ¯ 2 } tension (TTW) and { 10 1 ¯ 1 } compression (CTW) twins in Mg alloys under a mini-V-bending process. RSS analysis indicated that EFG and ECG Mg alloys are more favorable for the activity of TTW and less favorable for the activity of CTW when compared with AZ31 Mg alloy during a mini-V-bending process. However, RSS analysis was not effective in quantitatively predicting twin development. The relative activities of six deformation modes, accumulated twin fractions, and accumulated plastic strains were simulated via microstructure-based CPFEM modeling. Compared with RSS analysis, CPFEM precisely explained the twin behavior that has been experimentally observed in ECG and AZ31 Mg alloys. • The effects of initial texture and grain size in Mg alloys under mini-V-bending tests were investigated. • The micromechanical deformation behavior was studied using EBSD analysis, RSS criterion, and mesoscale CPFEM modeling. • Deformation twinning was more prominent in ECG and EFG Mg alloys than in AZ31 Mg alloy during the mini-V-bending. • In contrast to the RSS criterion, CPFEM modeling more accurately described the twin behavior observed in the experiments. • The primary deformation mode in ECG and AZ31 Mg alloys was basal a and pyramidal c + a slip, respectively. [ABSTRACT FROM AUTHOR]

Abstract Microstructure evolution in E-form and AZ31 magnesium (Mg) alloys was studied via ex-situ mini-V-bending tests. Initially, the E-form and AZ31 Mg alloys had different crystallographic textures and average grain-size distributions. Direct observation of microstructural evolution during the ex-situ mini-V-bending tests was experimentally observed via electron back-scatter diffraction (EBSD) technique. The EBSD results revealed how twin bands (TBs) developed at different punch strokes (PSs) in the deformed grains made a significant contribution to the localized deformation zones in both Mg alloys under the mini-V-bending process. Eventually, the TBs and grain boundaries (GBs) in the localized deformation zones were responsible for crack initiation sites in the tension region. At lower PSs, compression (CTW) and double (DTW) twins were more prominent in E-form than in AZ31 under the mini-V-bending process. High-resolution cross-sectional t-EBSD analysis showed that surface relief allowed the grains residing on the free surface to be less affected by stress concentration while the sub-surface grains were more affected by stress concentration, which promoted the development of twinning. Highlights • Microstructure evolution were studied via ex-situ mini-V-bending tests. • Direct observation during the ex-situ mini-V-bending tests was conducted via EBSD technique. • TBs and GBs in the localized deformation zones were responsible for crack initiation sites in the tension region. • CTW and DTW were more prominent in E-form Mg alloy than AZ31 Mg alloy under the mini-V-bending process. • High-resolution t-EBSD was conducted to reveal the deformation behavior of the grains residing on the free surface. [ABSTRACT FROM AUTHOR]

The heterogeneity of both deformation and twinning behaviors through the thickness direction in E-form Mg alloy sheets was investigated via conventional Erichsen testing at room temperature (RT). The microtexture heterogeneity through the thickness direction of the E-form Mg alloy sheets deformed by different punch strokes (PSs) is discussed in terms of deformation twinning and de-twinning. The evolution of the microtexture, twin and KAM (kernel average misorientation) of E-form Mg alloy sheets deformed by different PSs was analyzed via electron back-scattered diffraction (EBSD) technique. A crystal plasticity finite element method (CPFEM) based on a random mapping (RM) scheme was used to simulate the heterogeneities of the strain/stress states of E-form Mg alloy sheets through the thickness direction during an Erichsen test. The evolution of the strain/stress that developed in E-form Mg alloy sheets during Erichsen testing was analyzed for different regions through the thickness direction under different PSs. EBSD analysis revealed that tension (TTWs), compression (CTWs) and double (DTWs) twins were the main deformation mechanisms in the upper portions. However, in the lower portions, a change in the sign of strain/stress components during Erichsen testing resulted in a significant formation of TTWs in the early stages and in a de-twinning of TTWs in the later stages. [ABSTRACT FROM AUTHOR]

Deformation and failure behaviors of E-form magnesium (Mg) alloy sheets were investigated using a mini-V-bending test. The evolution of the microstructure and microtexture of the deformed E-form Mg alloy sheets (before and after failure) was analyzed via an electron back-scattered diffraction (EBSD) technique. Finite element analysis (FEA) was used to capture the heterogeneous distribution of longitudinal-strain components through the thickness direction under mini-V-bending at different punch strokes. The relationships between punch stroke, bending radius and longitudinal-strain at the tension and compression zones were established. EBSD analysis revealed that shear localization by dislocation slip along with compression and double twins were the main deformation mechanisms in the tension zone while tensile twins were a main deformation mechanism in the compression zone in E-form Mg alloy sheets during mini-V-bending. The effect that deformation twinning had on the crack propagation sites in E-form Mg alloy sheets was also investigated. The networks of compression { 10 1 ¯ 1 } and double { 10 1 ¯ 1 } − { 10 1 ¯ 2 } twins in the tension zone of E-form Mg alloy sheets were closely related to the crack propagation during mini-V-bending at near room temperature (RT). [ABSTRACT FROM AUTHOR]

The current study examined the deformation mechanisms, microstructure, and texture evolution in AZX311 Mg alloy sheets subjected to in-plane shear (IPS) deformation. Different levels of shear strains, with values 0.05, 0.10, and 0.15, were applied along the rolling direction (RD) using a specialized in-plane shear testing jig. The strain measurement for the applied shear deformation was conducted utilizing the digital image correlation (DIC) technique. The strain distribution was found to be nearly homogeneous over sufficiently large areas, thereby allowing the microstructural measurements to yield relevant statistical data. A thorough microstructural examination across the thickness using electron back-scattered diffraction (EBSD) revealed that the application of IPS strain led to the formation of a significant number of tensile twins (TTWs) in the sheet. This was evidenced by the emergence of two satellite peaks at the periphery of the pole figures. As the shear strain increased, the proportion of TTWs in the material also increased, encompassing the entire parent grain and leading to the formation of what has been termed as " all-twinned microstructure ". The microstructural and texture investigation after IPS deformation revealed that TTWs were the dominant deformation mechanism that defined the microstructure and texture under IPS deformation, while dislocation slip activity was dominated by prismatic slip, as evidenced by the resolved shear stress analysis in this study. Consequently, this research highlights the effect of IPS deformation on the microstructure and texture evolution throughout the thickness of an Mg alloy sheet and elucidates the underlying mechanisms. [Display omitted] • In-plane shear (IPS) deformation induces significant tensile twins throughout the thickness direction in the shear zone. • Imposing higher shear strains led to a predominantly twinned grain orientation throughout the parent grain. • Shear strain is uniform within the shear zone across varying shear strains and major contributor to the von-Mises strain. • RSS analysis revealed that the initial microstructure supports the activation of tensile twins and prismatic slip. • Tensile twins exerted a more significant influence on the evolution of microstructure/texture during the IPS deformation. [ABSTRACT FROM AUTHOR]

• Effect of IHT during the hot rolling on texture and formability of annealed AZ31 Mg alloy was investigated. • The basal texture was weakened during most of the IHT and AHT stages regardless of IHT conditions. • The TBL of the DTWs increased as hot rolling progressed and most of the TBLs decreased during the IHT and AHT stages. • Recrystallized grains in the IHT specimens showed a relatively weak basal texture compared with deformed grains. • The IE of annealed AZ31 Mg alloy have a proportional relationship with the EL, but is inversely proportional to the YS. In this study, we investigated the effect of intermediate heat treatment (IHT) on the texture evolution and stretch formability of annealed AZ31 Mg alloy sheets during different stages of hot rolling. Electron backscatter diffraction (EBSD) and X-ray diffraction (XRD) techniques were used to measure the crystallographic texture and to explain how IHT contributes to the texture evolution in hot-rolled specimens. The behavior of static recrystallization (SRX) during IHT was investigated to explain its role in weakening the basal texture in IHT specimens. Furthermore, t-EBSD was used to investigate the orientation distribution of recrystallized grains in the deformed matrix. Moreover, the effect that IHT can exert on the mechanical and Erichsen Index (IE) of annealed sheets was investigated at room temperature, and also at 100 and 200 °C. An analysis of the different IHT specimens indicated that the influence of IHT on the IE was significantly dependent on the measurement temperature. [ABSTRACT FROM AUTHOR]