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

Chen, Jie ; Wang, Zhijun ; Zhang, Haifeng ; Zhang, Hongtao ; Yang, Qingxiang ; Ye, Longhai

Abstract

The dynamic mechanical properties of GH4720Li nickel base superalloy under high and low strain rates in a widetemperature range have been studied, and a constitutive model with higher fitting progress have been established. Theexperimental results show that the abnormal phenomenon of dynamic mechanical properties of GH4720Li alloy appearsunder the condition of high strain rate. This is because the change of Cr (MO) content in precipitates and the change ofprecipitate morphology lead to the difference of dynamic mechanical properties of GH4720Li alloy at high and low strainrates. Besides, A new piecewise function model based on a phenomenological representation of the stress-strain curves isproposed 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 comparisonbetween calculated values and experimental values based on the new constitutive modeling shows that these methods forobtaining material constants k and C are valid and the new function model is significant for establishing constitutiveequations of Nickel-based superalloy GH4720Li in hot deformation processes.


Keyword(s)

Nickel-based superalloy; High strain rate, Low strain rate, Precipitate, Constitutive equation

 


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