CORRECTION OF FLOW CURVES AND CONSTITUTIVE MODELING OF AN AS-CAST N06625 NICKEL-BASED ALLOY

Abstract

On a Gleeble-3800 simulator, isothermal hot compression tests of an as-cast N06625 nickel-based alloy were conducted in a wide range of temperatures (950–1200 °C) and strain rates (0.1–50 s–1). Considering the influence of friction and adiabatic heating in the test, the flow curves were corrected. A modified Johnson-Cook, strain-compensated Arrhenius-type and modified Hensel-Spittel constitutive models were established based on the corrected flow curves. In a hot compression test, the flow stress is mainly affected by the coupling of the temperature, strain rate and strain, so the consideration of the coupling effect greatly affects the accuracy of the constitutive model. Moreover, different materials have different sensitivities to the three conditions. Therefore, the improved model in this paper can improve its universality and accuracy after adding relevant parts to it. The models were compared using the correlation coefficient (R) and average absolute relative error (AARE) to determine their accuracy in predicting the deformation behavior of the above alloy. According to our findings, the strain-compensated Arrhenius-type model provided the greatest forecast accuracy over the whole temperature and strain rate range. Under a certain temperature and strain rate, the modified Johnson-Cook model provided the best prediction accuracy.