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首页> 外文期刊>International Journal of Plasticity >A constitutive model for hcp materials deforming by slip and twinning: application to magnesium alloy AZ31B
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A constitutive model for hcp materials deforming by slip and twinning: application to magnesium alloy AZ31B

机译：hcp材料通过滑移和孪生变形的本构模型：在镁合金AZ31B中的应用

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A crystal-mechanics-based constitutive model, which accounts for both slip and twinning, has been developed for polycrystalline hcp materials. The model has been implemented in a finite-element program. The constitutive model is evaluated for the room-temperature deformation of the magnesium alloy AZ31B. By using comparisons between model predictions and macroscopically-measured stress-strain curves and texture evolution, we have deduced information about the dominant slip and twinning systems active at room temperature, and the values of the single-crystal parameters associated with slip and twin system deformation resistances. Our calculations show that the two main crystallographic mechanisms: (i) slip on basal (0001) <11 (2) over bar0>, prismatic {10 (1) over bar0} <11 (2) over bar0>, and pyramidal {10 (1) over bar1} <11 (2) over bar0> systems, and (ii) twinning on pyramidal {10 (1) over bar2} <(1) over bar 011> systems, play the dominant role in the deformation of magnesium at room temperature. However, to match the observed stress-strain curves, it is found necessary to account for non-crystallographic grain boundary related effects. We approximately account for these grain-boundary region accommodation effects by adding a suitably-weighted isotropic term to the flow rule. The isotropic plasticity term serves the important function of bounding the stress levels in the numerical calculations; it does not contribute to the crystallographic texture evolution. Overall, we show that a simple non-hardening crystal-mechanics-based constitutive model is able to reproduce the experimentally-measured stress-strain curves and crystallographic texture evolution in simple tension and compression on specimens made from an initially-textured rod, as well as plane strain compression experiments on specimens made from an initially-textured plate. (C) 2003 Elsevier Science Ltd. All rights reserved. [References: 28]
机译：已经针对多晶hcp材料开发了一种基于晶体力学的本构模型，该模型同时考虑了滑移和孪生现象。该模型已在有限元程序中实现。对于镁合金AZ31B的室温变形，评估了本构模型。通过使用模型预测与宏观测量的应力-应变曲线和织构演变之间的比较，我们推导了有关在室温下活跃的主要滑移和孪生系统的信息，以及与滑移和孪生系统变形相关的单晶参数的值抵抗。我们的计算表明，两个主要的晶体学机理：（i）在bar0>上在基面（0001）<11（2）上滑动，在bar0>上的棱柱形{10（1）}在bar0>上<11（2），以及金字塔形{10 （1）在bar1}系统上的<11（2）在bar0>系统上，以及（ii）在金字塔形{10（1）以上，bar2} <（1在之上011>系统上）孪生，在镁的变形中起主要作用在室温下。然而，为了匹配观察到的应力-应变曲线，发现有必要考虑与非晶体学晶界有关的影响。我们通过在流量规则中添加适当加权的各向同性项来近似地解释这些晶粒边界区域的调节作用。各向同性可塑性项在数值计算中起着限制应力水平的重要作用。它无助于晶体结构的演变。总的来说，我们表明，一个简单的基于非硬化晶体力学的本构模型能够以简单的拉伸和压缩方法对由初始纹理化的棒材制成的标本，再现实验测量的应力-应变曲线和晶体学织构演变。作为对由初始纹理化的板制成的标本进行平面应变压缩实验的方法。 （C）2003 Elsevier ScienceLtd。保留所有权利。 [参考：28]

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