Bending is a crucial operation in the sheet forming of Mg alloys for automotive and aerospace applications. In this work, three kinds of sheets from an AZ31 rolled plate, sheared at 0° (S0), 45° (S45), and 90° (S90) to the rolling direction, were subjected to three-point bending tests. In-situ digital image correlation (DIC) system was employed to capture the strain fields. Electron backscatter diffraction (EBSD) was used to examine the through-thickness microstructures. A crystal plasticity finite element method (CPFEM) incorporating twinning and slip mechanisms was developed to simulate the bending deformation. The texture effect on the neutral layer shift and twinning behaviors was systematically investigated in terms of both experiments and simulations. The results show that CPFEM effectively simulated the texture-dependent shifting behaviors of neutral layer and the associated twinning behaviors. Particularly, the spatial distributions of neutral layer across the entire bent plates were captured by both DIC and CPFEM. Additionally, some unusual twinning behaviors were analyzed in depth, such as the {10-12}-{10-12} secondary twins in S90, localized twin bands in S0, and the twin traces difference in S45. These findings reveal a close relationship between the neutral layer shift and twinning activity induced by the initial texture and strain levels. This work provides valuable insights into the bending deformation mechanisms of Mg alloys and has important implications for improving their formability and controlling springback.

Although magnesium-aluminum alloys, such as AZ80 and AZ91 have promising application potential in automotive, high-speed train and aerospace fields, their age-hardening response is generally not very appreciable. In this work, the aging-hardening response of AZ80 alloy was effectively enhanced by applying cold-rolling deformation before conducting conventional aging treatment at 200 °C. Compared to the directly aged sample, the yield strength of the pre-rolling and aged sample was increased by 35 MPa. Electron microscope examination confirmed that profuse {1011} and {1011}-{1012} twins, consisting of high density of dislocations and stacking faults, were generated by cold rolling. Blocky or ellipsoidal Mg₁₇Al₁₂ precipitates formed at the twin boundaries (TBs) during subsequent aging treatment. Crystallographic analysis indicated that the precipitates at {1011} TBs always held an identical Potter OR with both the matrix and twin, while the precipitates at {1011}-{1012} TBs exhibited three different ORs: Burgers OR, Potter OR and P-S OR with either the matrix or the twin. Moreover, recrystallized grains were found inside {1011}-{1012} double twins after peak-aging at 200 °C, implying that precipitation and recrystallization might occur concurrently along TBs at a relatively low temperature. It was speculated that the highly stored energy inside twins and the high elastic energy between the precipitates and twins were driving factors for the occurrence of recrystallization.

Although the non-basal precipitates, those not parallel to the basal plane, are more effective to block basal slip in Mg-Al alloys, the crystallographic orientation relationship (OR) between these precipitates and the α-Mg matrix has not been well established. In this work, the crystallography of the non-basal Mg₁₇Al₁₂ precipitates in AZ80 alloy was systematically investigated by transmission electron microscopy (TEM). By tilting to a suitable electron beam direction, different kinds of non-basal precipitates were recognized in TEM, and the following four new ORs between the non-basal Mg₁₇Al₁₂ precipitates and the matrix were revealed: OR − 1 : [2110]_α//[011]_β, (0111)_α//(011)_β; OR − 2 : [2110]_α//[011]_β, (0001)_α1° from (411)_β; OR − 3 : [2110]_α//[011]_β, (0001)_α//(011)_β, and OR − 4 : [2110]_α//[011]_β, (0001)_α//(100)_β. Furthermore, these ORs and their habit planes were explained using the edge-to-edge matching model. The findings in this work can provide some guidelines for designing the microstructure of Mg-Al alloys to enhance their precipitation hardening potential.