A viscoplastic constitutive model incorporating dynamic strain aging effect during cyclic deformation conditions

In this paper, a viscoplastic constitutive model previously proposed by the authors was extended to apply to the cyclic deformation analysis of the mo dified 9Cr-1Mo steel. A series of cyclic deformation tests were conducted o n modified 9Cr-1Mo steel at various temperatures, including those under ani sothermal conditions. Furthermore, cyclic evolution of state variables used in the authors' constitutive model was experimentally measured. Based on t he test results, cyclic softening behavior depending on the temperature and its history was introduced into the constitutive model. The extended model was applied to simulations of inelastic deformation behavior under monoton ic tension, stress relaxation, creep, isothermal cyclic deformations includ ing stress relaxation and anisothermal cyclic deformations. It was found th at the present constitutive model has a capability of describing the inelas tic deformation behavior of modified 9Cr-1Mo steel adequately at various lo ading conditions. (C) 2000 Elsevier Science Ltd. All rights reserved.