Advanced Modeling of Creep Behavior Under High Temperatures: Interplay of Strain Hardening, Damage, and Tensile Boundary Stress

Abstract This article proposes a comprehensive creep constitutive model that considers the strain-hardening effect during the initial creep stage, the damage accumulation characteristics throughout the creep period, and the boundary stress of tensile creep. Based on the concept of creep activation energy, the model incorporates the influence of temperature on creep deformation and employs a set of parameters to consistently describe creep behavior under different temperatures. The proposed model effectively captures the “U”-shaped creep strain rate curve throughout the entire creep period, which differs from the traditional theory that assumes a long-term steady-state creep stage. Additionally, it can describe the power-law breakdown phenomenon of creep strain rate and derive a creep life prediction formula based on the integration of damage parameters. Comparisons with experimental data from P92 and T92 alloys demonstrate that the model maintains high predictive accuracy across the overall range, with only some deviations in creep strain rate and creep life predictions under low-stress conditions. These results confirm the model's validity and highlight its potential for engineering applications.