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采用Gleeble-3800热模拟试验机,在温度为1173~1473 K,应变速率为0.01~10 s-1的变形条件下,对一种航空用高强度渗碳钢-9310钢进行热压缩实验,基于真应力-应变曲线,研究了两种高温变形流变应力的本构方程模型-位错模型和Sellars模型在该钢上的应用,根据动态再结晶是否发生,建立了不同热变形阶段下9310钢的流变应力本构方程。研究表明,在ε>0.1条件下的动态软化和稳态流变阶段中,基于位错密度和动态软化机制的位错模型方程,精度误差在15%以下,但该方程参数多,计算量大,而基于Sellars模型的本构方程,在低温热变形(T<1273 K)及大应变(ε>0.5)条件下的精度误差更小,且方程相对简单,便于应用。在高强渗碳9310钢的热加工生产中,建议采用Sellars模型作为大应变条件下流变应力的预报方程,精度误差控制在10%以下;为了提高方程精度,Sellars模型下由于动态再结晶软化引起的应力降低值Δσ中,相关参数的取值还有进一步修正的可能。
A Gleeble-3800 thermal simulation test machine was used to carry out the thermal compression test of a high-strength carburizing steel -9310 for aviation under the deformation conditions of 1173 ~ 1473 K and strain rate of 0.01 ~ 10 s-1. The stress-strain curves of two types of high-temperature deformation flow stress constitutive equation model - the Dislocation model and the Sellars model in the steel application, according to whether the dynamic recrystallization occurred, the establishment of different stages of hot deformation 9310 steel The flow stress constitutive equation. The results show that the accuracy error of dislocation model equation based on dislocation density and dynamic softening mechanism is less than 15% in the dynamic softening and steady-state rheological stages with ε> 0.1. However, this equation has many parameters and a large amount of calculation However, the constitutive equation based on Sellars model has less accuracy error under low temperature thermal deformation (T <1273 K) and large strain (ε> 0.5), and the equation is relatively simple and easy to apply. In the heat treatment of high-strength carburizing 9310 steel, the Sellars model is suggested as the predicting equation of the flow stress under the condition of large strain, the precision error is controlled below 10%. In order to improve the accuracy of the equation, the Sellars model is caused by the dynamic recrystallization softening The value of the stress reduction Δσ, the relevant parameters may be further amended.