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

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%.