Texture-dependent character of strain heterogeneity in Magnesium AZ31 under reversed loading

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• 作者：Enver Kapan ; Nima Shafaghi ; Sevinc̣ Uc̣ar ; C. Can Aydıner ; ^{can.aydiner@boun.edu.tr}
• 关键词：Strain measurement ; Magnesium alloys ; Twinning ; Strain heterogeneity ; Shear banding
• 刊名：Materials Science and Engineering: A
• 出版年：2017
• 出版时间：27 January 2017
• 年：2017
• 卷：684
• 期：Complete
• 页码：706-711
• 全文大小：1065 K
• 卷排序：684

文摘

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 µm 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°±45° 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.