Texture-dependent character of strain heterogeneity in Magnesium AZ31 under reversed loading
Texture-dependent character of strain heterogeneity in Magnesium AZ31 under reversed loading
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DOI：
10.1016/j.msea.2016.12.085
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发表时间：
2017-01-27
期刊：
影响因子：
6.4
通讯作者：
Aydiner, C. Can
中科院分区：
文献类型：
--
作者：
Kapan, Enver;Shafaghi, Nima;Aydiner, C. Can
根据操作的微观机制和晶体学织构，先天应变局部化在多晶体的微观结构的长度尺度可以空间协调，以诱导宏观应变局部化。这是材料性能和建模的一个挑战，当变形镁合金具有强拉伸孪晶时，在变形镁合金中观察到这种行为。利用原位多表面图像相关技术，对具有一致的11 μ m晶粒尺寸的挤压和轧制织构的样品进行了压缩拉伸实验。虽然这两种纹理的样品都表现出清晰的孪晶平台，应力水平接近（轧制/挤出样品为90/99 MPa），但应变局部化模式在几何结构和强度方面都有很大不同。轧制后的试样呈现出剪切面固定的尖锐剪切带结构。挤出样品表现出应变局部化，其不是宏观+/-45度剪切形式，并且强度弱得多（约为2倍）。一旦负载被逆转和拉伸孪晶被停用，应变调节很大程度上均匀化的两个纹理在解孪晶和随后的高硬化阶段。
Depending on operational micromechanisms and crystallographic texture, the innate strain localization at microstructural length scales of a polycrystal can spatially coordinate to induce macroscopic strain localization. A challenge for material performance and modeling, this behavior is observed in wrought Magnesium alloys when they deform with heavy tensile twinning. With in-situ, multi-surface image correlation, a compression tension experiment is implemented on samples with extrusion and rolling texture that have a consistent 11 mu m grain size. While samples of both textures exhibit a clear twin plateau with close stress levels (90/99 MPa for rolled/extruded samples), the strain localization patterns are vastly different, both in terms of geometric structure and intensity. Rolled sample exhibits sharp shear banding structures with a fixed plane of shear. Extruded sample exhibits strain localization that is not in macroscopic +/- 45 degrees shear form and much weaker in intensity (by about a factor of 2). Once the load is reversed and the tensile twin is deactivated, strain accommodation largely homogenizes for both textures during detwinning and subsequent high hardening stages.