An experimental study of anisotropic fracture behavior of rolled AZ31B magnesium alloy under monotonic tension
An experimental study of anisotropic fracture behavior of rolled AZ31B magnesium alloy under monotonic tension
复制标题
DOI：
10.1016/j.msea.2021.142193
复制
发表时间：
2021-10
期刊：
影响因子：
--
通讯作者：
Yuqian Wang;Qin Yu;Yanyao Jiang
中科院分区：
文献类型：
--
作者：
Yuqian Wang;Qin Yu;Yanyao Jiang
变形镁合金的室温力学响应表现出明显的各向异性。镁合金的断裂行为，特别是其对材料取向的依赖，尚未得到很好的研究。本文研究了AZ31B镁合金轧制方向（RD）的各向异性断裂行为，对5种不同材料取向（θ= 0°、22.5°、45°、67.5°和90°）的Mg板试样进行了单调拉伸实验。轧制镁合金的拉伸断口表现出明显的各向异性。在宏观尺度上，在θ= 22.5°和45°处，剪切断裂呈现出相对平坦的断口。显微组织分析表明，这两种材料取向的断裂是由基底滑移引起的局部剪切作用的结果，裂纹的萌生和扩展都是由基底滑移引起的。相反，在θ= 0°、67.5°和90°的拉伸下，出现了由脊状和岛状组成的不规则表面的脆性断裂。当θ= 0°时，微裂纹附近的显微组织分析证实，裂纹形成于压缩和压缩-拉伸双孪晶的尖端和/或边界。当θ= 67.5°和90°时，微裂纹起源于高角度晶界裂纹，这可能是由于无共带孪晶晶界和第三次拉-压-拉孪晶对高角度晶界的冲击引起的应力集中引起的。
Wrought magnesium (Mg) alloys display pronounced anisotropy in their room-temperature mechanical responses. The fracture behavior of Mg alloys, especially its reliance of material orientation, has not been well explored. The current work is an investigation of the anisotropic fracture behavior in a rolled AZ31B Mg alloy by carrying out monotonic tension experiments of specimens taken from the rolled Mg plate with five different material orientations (θ= 0°, 22.5°, 45°, 67.5° and 90°) with respect to the rolled direction (RD). Significant anisotropy is exhibited in the tensile fracture of the rolled Mg alloy. At the macroscopic scale, shear fracture displaying relatively flat fracture surface is exhibited from tension atθ= 22.5° and 45°. Microstructural analysis reveals that fracture at these two material orientations is a result of localized shearing accommodated by basal slips from which both crack initiation and propagation are originated. In contrast, under tension atθ= 0°, 67.5° and 90°, brittle-like fracture is shown where irregular-shaped surfaces composed by ridges and islands are observed. Forθ= 0°, microstructural analysis in the vicinity of microcracks confirms that crack forms at the tip and/or boundary of compression and compression-tension double twins. For the cases ofθ= 67.5° and 90°, microcrack initiation is due to high-angle grain boundary cracking, which is likely caused by stress concentration due to impingements of none co-zone twin-twin boundaries and tertiary tension-compression-tension twins on the high-angle grain boundaries.