Constitutive model of GH4720Li high temperature nickel base alloy at high strain rate and large temperature range

Abstract

The dynamic mechanical properties of GH4720Li nickel base superalloy under high and low strain rates in a wide temperature range have been studied, and a constitutive model with higher fitting progress have been established. The experimental results show that the abnormal phenomenon of dynamic mechanical properties of GH4720Li alloy appears under the condition of high strain rate. This is because the change of Cr (MO) content in precipitates and the change of precipitate morphology lead to the difference of dynamic mechanical properties of GH4720Li alloy at high and low strain rates. Besides, A new piecewise function model based on a phenomenological representation of the stress-strain curves is proposed to describe the constitutive equation of Nickel-based superalloy GH4720Li of stress-strain curves. Meanwhile, new methods to obtain the material constant k and C are proposed to predicted accurately the flow stress. The comparison between calculated values and experimental values based on the new constitutive modeling shows that these methods for obtaining material constants k and C are valid and the new function model is significant for establishing constitutive equations of Nickel-based superalloy GH4720Li in hot deformation processes.