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.

中文翻译：

---

预孪生及热处理对AZX311镁合金成形性能的影响

在本研究中，研究了预应变诱导拉伸孪晶 (TTW) 和控制热处理对 AZX311 镁合金板材成形性能的影响。使用面内压缩 (IPC) 技术沿轧制方向 (RD) 施加 4% 的压缩应变，对板材进行预应变，以引入 TTW。随后将预应变 (PS) 样品分别在 250 °C、350 °C 和 400 °C 下热处理 1 小时，分别称为 PSA1、PSA2 和 PSA3。进行埃里克森杯突试验以评估板材样品在不同初始条件下的可成形性。结果表明，与轧制样品相比，在 250 °C 下热处理 1 小时的 PS 样品的埃里克森指数 (IE) 有所下降，而 PSA2 和 PSA3 样品的 IE 值有所增加。显微织构分析表明，大部分通过预孪晶生成的 TTW 在 250 °C 下保持稳定；然而，由于该温度下的热活性增强，与 PS 样品相比，在 350 °C 时孪晶体积分数降低至 41%。此外，PSA2 样品在样品的某些区域显示出严重的晶粒粗化，并且此类晶粒的比例在 PSA3 样品中有所增加。与轧制样品相比，PSA2 样品的拉伸成型性（IE 值）增加了 32.3%。此外，对埃里克森试验下失效时变形样品的分析表明，PS 和 PSA1 样品中发生了相当大的解孪，而 PSA2 和 PSA3 样品在拉伸成型过程中位错滑移活动占主导地位。除了解孪生和位错滑移之外，埃里克森测试后所有样品中还观察到变形孪晶。因此，这项工作强调了通过预孪晶和热处理进行织构控制及其基本机制的重要性，及其对 AZX311 镁合金板材室温 (RT) 拉伸成形性的影响。