Inelastic constitutive equations for modified 9Cr-1Mo steel under nonisothermal cyclic deformation conditions. 2. Extension of unified constitutive model incorporating dynamic strain aging effect and its simulations

Based on inelastic behavior of modified 9Cr-1Mo steel described in the first report, the unified constitutive model proposed by the authors was extended for cyclic deformations, including nonisothermal conditions. In the constitutive model, cyclic softening behavior was expressed by decreasing an asymptotic value of back stress with accumulation of inelastic strain. Most of the constants in the constitutive model were determined as a function of the temperature in order to calculate stress-strain relationships under nonisothermal conditions. To evaluate the validity of the constitutive model, it was applied to analysis of inelastic behavior under monotonic tension, stress relaxation, creep, isothermal cyclic deformations including stress relaxation and nonisothermal cyclic deformations. It was found that the present constitutive model was successful in describing the inelastic behavior of the steel adequately. (author)