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采用Gleeble-3500热模拟试验机,研究Mg-13Gd-4Y-2Zn-0.6Zr合金在300℃~500℃、应变速率0.001s-1~1s-1时的高温流变行为,获得了合金的真应力-应变曲线。实验结果表明,随着温度上升、应变速率下降,合金的流变应力、峰值应力和峰值应变均减小。利用真应力-应变数据,进行数值拟合、回归计算,求得合金的热变形激活能Q为273.4kJ·mol-1,并建立该合金的流变应力本构模型,该模型结果与实验数据的最大误差小于5%。同时,根据动态材料模型,计算并得到了该合金在不同真应变下的热加工图,分析了其变化规律。并以真应变为0.7的热加工图为依据,结合材料的微观组织,确定了该合金的最佳变形工艺为480℃/0.01s-1。利用金相图解释了各失稳区的组织演变特点。
The high-temperature rheological behavior of Mg-13Gd-4Y-2Zn-0.6Zr alloy at 300 ℃ ~ 500 ℃ and strain rate of 0.001s-1 ~ 1s-1 was studied by Gleeble-3500 thermal simulation test machine. stress-strain curve. The experimental results show that as the temperature rises, the strain rate decreases and the flow stress, peak stress and peak strain of the alloy decrease. Using true stress-strain data, numerical simulation and regression calculation were carried out to find that the heat deformation activation energy Q of the alloy was 273.4 kJ · mol-1, and the flow stress constitutive model of the alloy was established. The results of the model are in good agreement with the experimental data The maximum error is less than 5%. At the same time, according to the dynamic material model, the hot working diagram of the alloy under different true strains was calculated and obtained, and its variation was analyzed. Based on the hot working diagram of true strain 0.7, the optimal deformation process of the alloy was determined to be 480 ℃ / 0.01s-1 based on the microstructure of the material. The morphological evolution of each instability zone is explained by the metallographic diagram.