An Improved Arrhenius Constitutive Model and Three-Dimensional Processing Map of a Solution-Treated Ni-Based Superalloy

Abstract

The hot deformation behaviors of a solution-treated Ni-based superalloy are investigated by hot compression tests over wide ranges of strain rate and forming temperature. Based on the experimental data, the effects of forming temperature and strain rate on the hot deformation behaviors are discussed in detail. Considering the effects of strain on material constants, comprehensive constitutive models are developed to describe the relationships between the flow stress, strain rate and forming temperature for the studied superalloy. The three-dimensional processing map is constructed to optimize the hot working parameters. Meanwhile, the microstructures are analyzed to correlate with the processing map. It is found that the flow stress is sensitive to the forming temperature, strain rate and deformation degree. With the increase of forming temperature or the decrease of strain rate, the flow stress significantly decreases. The predicted flow stresses agree well with experimentally measured results, which confirm that the developed constitutive model can accurately estimate the flow stress of the studied superalloy. The three-dimensional processing map shows that the optimum deformation windows for hot working are the domains with 980–1,040°C or 0.001–0.1 s−1$${{\rm{s}}^{- {\rm{1}}}}$$ when the strain is 0.6. Also, it is found that the dynamically recrystallized grain size increases with the increase of forming temperature or the decrease of strain rate.

Keywords

• alloy
• hot deformation
• constitutive model
• processing map
• microstructure
• 81. materials science
• 83.10.gr constitutive relations
• 83.50.-v deformation and flow