Effects of initial microstructure on the microstructural evolution and stretch formability of warm rolled Mg–3Al–1Zn alloy sheets
Effects of initial microstructure on the microstructural evolution and stretch formability of warm rolled Mg–3Al–1Zn alloy sheets
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DOI：
10.1016/j.msea.2013.08.067
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发表时间：
2013-12
期刊：
影响因子：
6.4
通讯作者：
Xinsheng Huang;Kazutaka Suzuki;M. Yuasa;Y. Chino
中科院分区：
文献类型：
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作者：
Xinsheng Huang;Kazutaka Suzuki;M. Yuasa;Y. Chino
研究了Mg-3Al-1 Zn（AZ 31）镁合金板材在225 °C温轧时两种不同初始组织的单道次差速轧制的组织演变和拉伸成形性能。将平均晶粒尺寸分别为~470 μm和~19 μm的铸锭和在550 °C高温下通过一个道次轧制的铸锭用作起始材料。两种温轧板在轧制状态下均表现出变形组织，在随后的退火过程中由于静态再结晶而出现织构随机化。具有大的取向扩展的新的再结晶晶粒倾向于保持在母变形晶粒和孪晶宿主的原始取向上。对于晶界形核和双孪晶形核，静态再结晶优先发生在变形晶粒的侧面和双孪晶内部，双孪晶轴向轧制方向（RD）倾斜，最终退火织构稳定，基极向RD倾斜。对于由铸锭温轧而成的板材，由于大变形晶粒内部的储能较少而导致的不完全再结晶导致织构弱化不足和组织不均匀。与传统的AZ 31合金板相比，由于弱化的织构，这两种板具有改善的拉伸成形性。受益于较弱的基底织构和更均匀的显微组织，在550 °C下轧制然后在225 °C下温轧的板表现出8.2的更高的埃里克森值，与直接从铸锭温轧的板的埃里克森值（6.1）相比。
Microstructural evolution and stretch formability of Mg–3Al–1Zn (AZ31) magnesium alloy sheets warm rolled at 225 °C by a single differential speed rolling pass with two different initial microstructures were investigated. A cast ingot and that rolled by one pass at a high temperature of 550 °C with average grain sizes of ~470 μm and ~19 μm, respectively, were used as starting materials. Both warm rolled sheets exhibit deformation microstructure in as-rolled condition and the occurrence of texture randomization during subsequent annealing as a result of static recrystallization. New recrystallized grains with a large orientation spread tend to persist in the original orientations of parent deformed grains and twin hosts. Regarding the nucleation sites at pre-existing grain boundaries and double twins, static recrystallization preferentially occurs at the sides of deformed grains and within double twins with theirc-axes inclining toward the rolling direction (RD), resulting in a stable end annealing texture with a basal pole tilting toward the RD. For the sheet warm rolled from a cast ingot, incomplete recrystallization originating from less stored energy in the interiors of large deformed grains results in an insufficient texture weakening and an inhomogenous microstructure. Both sheets possess an improved stretch formability compared with conventional AZ31 alloy sheets due to the weakened textures. Benefiting from a weaker basal texture and a more homogenous microstructure, the sheet rolled at 550 °C followed by warm rolling at 225 °C exhibits a higher Erichsen value of 8.2 compared with that (6.1) of the sheet warm rolled directly from a cast ingot.