Microstructure and texture evolution during porthole die extrusion of Mg-Al-Zn alloy
Microstructure and texture evolution during porthole die extrusion of Mg-Al-Zn alloy
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DOI：
10.1016/j.jmatprotec.2018.05.003
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发表时间：
2018-09
影响因子：
6.3
通讯作者：
Liang Chen;Jixiao Zhang;Jianwei Tang;Gaojin Chen;Guoqun Zhao;Cunsheng Zhang
中科院分区：
文献类型：
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作者：
Liang Chen;Jixiao Zhang;Jianwei Tang;Gaojin Chen;Guoqun Zhao;Cunsheng Zhang
研究了分流模挤压AZ 31镁合金时不均匀组织的形成机理。重点研究了挤压型材焊缝区和基体区的两条流线，并分析了组织和织构的演变规律。结果表明：（1）焊接区流线：在劈裂阶段后发生了完全的动态再结晶（DRX），显微组织由几个微米的等轴晶组成。劈裂阶段形成强烈的剪切结构，轴向与法向有偏差。然后，在焊接阶段，基面旋转到与法线方向垂直。主要织构被确定为<0001>//ND和{0001}<11−20>织构，而这两种组分的分数在挤出过程中变化显著。(ii)基体区流线：沿整个流线沿着保留有粗大的拉长晶粒，表明发生了部分动态再结晶。此外，{10-12} <10−11>延伸孪晶出现在粗的未DRX晶粒内。未反相艾德化晶粒的基面倾向于垂直于艾德化方向，并有一个偏离角，同时还可以观察到{11-20}<10−10>织构。然而，DRXed晶粒没有形成具有一定图案的取向集中。
This study reports the formation mechanism of inhomogeneous microstructure in AZ31 Mg alloy extruded by porthole die. Two streamlines corresponding to welding and matrix zones of the extruded profile were focused, and the evolution of microstructure and texture was investigated. The results show that (i) Welding zone streamline: The complete dynamic recrystallization (DRX) occurred after splitting stage, and the microstructure consists of equiaxed grains with several microns. Strong shearing texture is formed during splitting stage, and thec-axis has a deviation with normal direction. Then, the basal plane rotates to be perpendicular with normal direction during the welding stage. The main textures are identified as <0001> //ND and {0001}<11−20> textures, while the fraction of these two components varies significantly during extrusion process. (ii) Matrix zone streamline: The coarse elongated grains were reserved along the whole streamline, which indicates the occurrence of partial DRX. Moreover, the {10–12} <10−11> extension twins appear inside the coarse unDRXed grains. The basal plane of unDRXed grains tends to be perpendicular to ED direction with a deviation angle, and the {11–20}<10−10> texture can also be observed. However, the orientation concentration with certain pattern was not formed for DRXed grains.