Incoloy 800H高温变形流动应力预测模型

CONSTITUTIVE MODELING FOR ELEVATED TEMPERATURE FLOW BEHAVIOR OF INCOLOY 800H SUPERALLOY

采用Gleeble-1500热模拟实验机研究了Incoloy 800H合金在变形温度为1273-1473 K和应变速率为0.01-10 s^(-1)条件下的流动应力行为.采用双曲正弦函数建立了Incoloy 800H高温条件下的流动应力本构方程,以六次多项式考虑了应变量耦合因素对本构关系的影响.研究结果表明,Incoloy 800H在热压缩变形过程中,低应变速率和高应变速率条件下分别呈动态软化和动态回复特征,流动应力随应变速率的增加而增加,随温度的升高而降低;采用应变的六次多项式拟合得到的本构关系流动应力预测值与实验值吻合较好,绝大多数(95%)情况下预测的误差小于6.5%,平均相对误差仅为3.15%.

In order to realize accurate numerical simulation of rolling, forging, extrusion of Incoloy 800H superalloy and formulate reasonable process parameters of hot working, the flow stress behaviors of Incoloy 800H superalloy were investigated in the temperature range of 1273-- 1473 K and strain rate range of 0.01--10 s^-1 on Gleeble-1500 thermo simulation machine. Utilizing hyperbolic sine function and introducing the strain factor with six polynomial fitting, the constitutive equations of flow stress of Incoloy 800H superalloy at high temperature were established, then the accuracy of the constitutive equation was verified. The results showed that during the hot compression deformation of Incoloy 800H superalloy, the characteristics of dynamic softening and dynamic recovery were observed at lower strain rates and high strain rates conditions, respectively, flow stress increased with increasing strain rate, decreased with increasing temperature; the flow stress of Incoloy 800H superalloy predicted by the proposed models with 6th order polynomial fit agrees with the experimental value well, relative error is not more than 6.5% at the overwhelming majority （95%） cases of the deformation conditions, and average relative error is only 3.15%.