Deformation and fracture behaviors of AZ31B Mg alloy at elevated temperature under uniaxial compression
Deformation and fracture behaviors of AZ31B Mg alloy at elevated temperature under uniaxial compression
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AZ31B镁合金单轴压缩高温变形与断裂行为
DOI：
10.1016/j.jallcom.2018.12.260
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发表时间：
2019-04-30
影响因子：
6.2
通讯作者：
Liu, Pengtao
中科院分区：
文献类型：
--
作者：
Jia, Weitao;Ma, Lifeng;Liu, Pengtao
通过单轴压缩实验和有限元模拟，研究了铸态AZ 31 B镁合金在较宽温度和应变速率范围内的变形和断裂行为。讨论了流变应力的应变率和温度敏感性、断口形貌、断裂临界应变、断裂判据及相关机理。结果表明，在相对较低的温度和较高的应变速率下，可以容易地产生所观察到的由微裂纹的萌生和扩展引起的应力的急剧变化。单轴压缩下沿剪切方向容易形成沿着向的剪切变形带，这是压缩过程中产生约45 °剪切开裂的主要原因，而球状析出物的存在对交叉剪切裂纹的形成有很大贡献。断裂模式和功率耗散效率之间存在很强的相关性，即，交叉和平行剪切开裂会显著降低效率。Freudenthal断裂准则对AZ 31 B镁合金热成形过程中的裂纹萌生和断裂位置具有较好的预测能力，适用于AZ 31 B镁合金热成形过程。通过高速摄影和数值模拟相结合的方法，成功地获得了临界开裂应变和弗赖登塔尔准则的临界损伤值。本文的数学分析表明，临界开裂应变与Ln（Zener-Hollomon参数，Z）之间存在线性关系，临界损伤与Ln Z之间也存在线性关系。针对AZ 31 B镁合金的高应变率和温度敏感性，Freudenthal断裂准则应进行优化。(C)2018爱思唯尔B. V.保留所有权利。
The deformation and fracture behaviors of as-cast AZ31B Mg alloy were studied by uniaxial compression experiments and finite element simulations with wide ranges of temperature and strain rate. The strain-rate and temperature sensitivities of flow stress, fracture morphology, critical strain to fracture, fracture criteria and related mechanism were discussed. Results show that the observed sharp in stress caused by micro-cracks initiation and propagation can be readily produced at relatively low temperatures and high strain rates. Shear deformation bands are easily formed along the shear direction under uniaxial compression, which are the main reasons for approximately 45 degrees shear cracking during the compression, and the presence of spheroidal precipitates makes a great contribution to the formation of crossed shear cracks. There exists a strong correlation between the fracture mode and power dissipation efficiency, i.e., the crossed and parallel shear cracking can significantly reduce the efficiency. Freudenthal fracture criterion is applicable to hot forming of AZ31B alloy due to its accurate prediction of the cracking initiation and fracture position under uniaxial compression. The critical cracking strain and further the critical damage value of Freudenthal criterion can be successfully achieved by combining the high-speed photography and numerical simulation. The present mathematical analysis indicates that a linear relationship exists not only between the critical cracking strain and Ln(Zener-Hollomon parameter, Z) but also between the critical damage and LnZ. In response to high strain-rate and temperature sensitivities of AZ31B alloy, the Freudenthal fracture criterion should be optimized. (C) 2018 Elsevier B.V. All rights reserved.