AA6082铝合金热变形损伤本构模型Damage constitutive model for thermal deformation of AA6082 aluminum alloy

利用Gleeble-1500热力模拟试验机在温度为425~525 ℃、应变速率为0.01~1 s^-1条件下对AA6082铝合金进行热拉伸试验，研究该合金的热变形行为。结果表明：变形温度、应变速率和应变对AA6082铝合金的流变应力影响显著，流变应力随变形温度的升高而下降，随应变速率的提高而增加；材料热变形经历了应变硬化段、稳态变形段和由损伤引起的流变应力陡降段。建立AA6082铝合金热变形统一黏塑性损伤本构模型，该模型综合考虑位错、硬化、损伤、应变、应变速率和温度等因素，借助遗传算法工具箱确定模型中材料常数。该模型能够较好地预测AA6082铝合金热变形时的流变应力，同时可以较好地描述材料的损伤演化行为。

Thermal deformation tests of AA6082 aluminum alloy were conducted by thermal-mechanical simulator Gleeble-1500 in the temperature range of 425-525 ℃ and strain rate of 0.01-1 s^-1 to investigate the thermal deformation behavior. The results show that the flow stress of AA6082 aluminum alloy is significantly influenced by temperature, strain rate and strain. The flow stress increases with decreasing temperature and increasing strain rate. The thermal deformation goes through strain hardening, steady-state stage and steep-fall stage of flow stress. The unified viscoplastic damage model of AA6082 aluminum alloy was established, taking into account of many factors, such as dislocation, hardening, damage, strain, strain rate and temperature. Material constants in the model were determined by genetic algorithm tool. The model can accurately predict the flow stress of AA6082 aluminum alloy in thermal deformation and describe the damage evolution.

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