A constitutive model to describe high temperature flow behavior of AZ31B magnesium alloy processed by equal-channel angular pressing
A constitutive model to describe high temperature flow behavior of AZ31B magnesium alloy processed by equal-channel angular pressing
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DOI：
10.1016/j.msea.2019.03.106
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发表时间：
2019-04
期刊：
影响因子：
--
通讯作者：
M. Arun;U. Chakkingal
中科院分区：
文献类型：
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作者：
M. Arun;U. Chakkingal
等通道转角挤压（ECAP）是一种用于在金属和合金中形成超细晶粒显微组织的众所周知的工艺。在这项研究中，AZ31B镁合金的热变形行为已被评估为ECAP道次和工艺路线的函数。采用BC和C工艺路线，使用120 °的模具角，对试样进行三道ECAP。在应变速率范围为0.01至10 s-1和温度范围为250至400 ° C的条件下进行等温热压缩试验，并生成流动曲线。将所产生的流动曲线数据拟合到用于描述热加工行为的标准本构方程，并确定活化能。结果表明，热变形激活能降低后，ECAP过程，这可能与晶粒细化。活化能从退火条件（晶粒尺寸：29 μ m）下的161.6 kJ/mol降低到路线3BC（晶粒尺寸：4.7 μ m）的145.3 kJ/mol和路线3C（晶粒尺寸：4.9 μ m）的132.3 kJ/mol。利用Zener Hollomon参数建立了各种ECAP道次的峰值流动应力预测方程，与实验观察值吻合较好。
Equal channel angular pressing (ECAP) is a well-known process for developing an ultrafine-grained microstructure in metals and alloys. In this study, the hot deformation behavior of an AZ31B Mg alloy has been evaluated as a function of ECAP passes and processing routes. Specimens were subjected to three passes of ECAP using a die angle of 120° using processing routes BCand C. Isothermal hot compression testing at strain rate ranging from 0.01 to 10 s−1and temperatures ranging from 250 to 400 °C were conducted and flow curves generated. The flow curve data generated were fitted to standard constitutive equations used to describe hot working behavior and the activation energies were determined. It was observed that the activation energies for hot deformation decreased after ECAP and this can be related to the grain refinement due to the ECAP process. Activation energy decreased from 161.6 kJ/mol in the annealed condition (grain size: 29 μm) to 145.3 kJ/mol for route 3BC(grain size: 4.7 μm) and 132.3 kJ/mol for route 3C (grain size: 4.9 μm). Equations for predicting the peak flow stress for various ECAP passes has been generated using the Zener Hollomon parameter and these are in agreement with the experimentally observed values.