Towards Interrelating the Nature of High Temperature Stress–Strain Curves and Creep Curves with Concomitant Microstructure Evolution

Constitutive relationship for high temperature deformation is generally based on the presence of stable microstructure and constant flow stress or strain rate, independent of strain. However, prior to and subsequent to steady state there appears, respectively, the transient and accelerated flow of materials both in strain rate and stress-controlled plastic deformation tests as shown by different stages of stress–strain and creep curves. In this work, an attempt is made to explain the transient flow behavior by continued variation in work hardening and dynamic recovery whereas the accelerated flow is explained by concurrent deformation-induced microstructure and damage evolution. For this purpose, the stress–strain curves, creep curves, microstructural and substructural evolution in a range of metallic systems are analyzed and the relationships between transient flow in strain rate and stress-controlled deformation are established. A similar approach was extended to analyze the accelerated flow in the two cases. There appear wide variations in morphology and length scale of micro/substructure, which result in strain-dependent flow stress. This leads to obeying a self-organized concurrent structure-flow property correlation during deformation.