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在Gleeble-1500热模拟仪上进行热压缩实验,研究在变形温度250~450°C、应变速率0.0005~0.5 s-1时淬火状态下的7005铝合金的热变形行为。实验结果表明:淬火状态7005合金的流变应力受变形温度和应变速率的双重影响,热变形过程中的流变应力可用Zener-Hollomon参数的指数型方程表示。通过比较本构方程计算出的流变应力和实验测量的流变应力发现预测结果和实验结果有很好的相符性。基于动态材料模型,在真应变为0.1、0.3和0.5处构建了淬火状态下的7005铝合金的热加工图。通过加工图分析及微观组织观察发现合金的最优热加工区域为:270~340°C,0.05~0.5 s-1,在该区域内变形时合金发生了合理的动态再结晶行为。合金的流变不稳定性与绝热剪切带以及局部流变的产生有关。因此,为获取满意的性能,在热加工时应避开这些不稳定的区域。
Thermal compression tests were carried out on a Gleeble-1500 thermal simulator to investigate the thermal deformation behavior of 7005 aluminum alloy under quenching conditions at a strain rate of 250 to 450 ° C and a strain rate of 0.0005 to 0.5 s-1. The experimental results show that the flow stress of the quenched 7005 alloy is affected by the deformation temperature and the strain rate. The flow stress in the hot deformation process can be expressed by the exponential equation of the Zener-Hollomon parameter. Comparing the flow stress calculated by the constitutive equation with the experimental flow stress, we find that the predicted result is in good agreement with the experimental one. Based on the dynamic material model, a hot working diagram of 7005 aluminum alloy in quenched condition was constructed at true strains of 0.1, 0.3 and 0.5. Through the processing diagram analysis and microstructure observation, it is found that the optimum hot working area of the alloy is 270 ~ 340 ° C and 0.05 ~ 0.5 s-1, and the dynamic recrystallization behavior of the alloy is reasonable during the deformation. The rheological instability of the alloy is related to the adiabatic shear band and the generation of local rheology. Therefore, to obtain satisfactory performance, these unstable areas should be avoided during hot working.