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通过高温热压缩试验,得到经DP工艺处理的GH4169合金在变形温度为900~1060℃、应变速率为0.001~0.5 s~(-1)、压缩量为70%条件下的真应力-真应变曲线,依据流变曲线特征,界定出加工硬化-动态回复和动态流变软化两个阶段,建立了相应的新型高温流变本构模型,同时观察了变形显微组织,进行了定量金相统计分析。结果表明:GH4169合金高温压缩显微组织中的动态再结晶晶粒尺寸随变形温度的升高或应变速率的降低而逐渐增大;δ相含量逐渐减少,在1060℃时基本消失。通过引入标准统计参数——相关系数和平均相对误差绝对值,表明预测值和实际试验数值吻合度较高,所建立的本构方程可以用于准确预测经DP工艺处理的GH4169合金热成形过程中的应力值和热成形工艺优化。
The true stress-true strain curves of GH4169 alloy treated by DP process were obtained by high-temperature thermal compression test under the conditions of deformation temperature of 900 ~ 1060 ℃, strain rate of 0.001 ~ 0.5 s ~ (-1) and compression amount of 70% According to the characteristics of the rheological curve, the two stages of work-hardening-dynamic recovery and dynamic rheological softening were defined. Corresponding new high-temperature rheological constitutive models were established. Meanwhile, the deformation microstructure was observed and the quantitative metallographic analysis . The results show that the grain size of dynamic recrystallization in the high temperature compression microstructure of GH4169 alloy increases with the increase of deformation temperature or strain rate; the content of δ phase decreases gradually and disappears basically at 1060 ℃. By introducing the standard statistical parameters - the correlation coefficient and the absolute value of the average relative error, it shows that the predicted value is in good agreement with the actual experimental value. The constitutive equation can be used to accurately predict the hot forming process of GH4169 alloy treated by DP process The stress value and thermoforming process are optimized.