Constitutive modeling for the creep-ratcheting interaction of 0Cr18Ni10Ti stainless steel at high temperature

Abstract

The 0Cr18Ni10Ti stainless steel serves as a crucial component in the construction of reactor piping, which is subjected to complex cyclic loadings at high temperatures. Hence, undertaking both experimental observation and computational modeling to explore the cyclic deformation behavior of this material is of significant importance. Cyclic experimental investigations of 0Cr18Ni10Ti stainless steel with various holding waveforms and holding times were conducted at 623 K. The results reveal that the holding variables influence on the cyclic responses, presenting a creep-ratcheting interaction. A nonlinear static recovery factor is integrated into the kinematic hardening equation within a unified visco-plastic (UVP) framework to assess the effects of these holding variables on creep-ratcheting interaction. Additionally, a nonlinear static recovery factor associated with isotropic resistance is incorporated into the isotropic hardening equation to account for the stress relaxation during holding intervals. The derived results demonstrate that this modified UVP constitutive model can reasonably simulate the creep-ratcheting interaction of 0Cr18Ni10Ti stainless steel at 623 K. Particularly, it accurately captures the stress amplitude evolution observed during sustained peak strain and the ratcheting strain accumulation while maintaining peak stress. The proposed model provides a fundamental basis for evaluating the cyclic deformation responses of 0Cr18Ni10Ti stainless steel, as used within nuclear reactor environments.