Modeling the Cycle-Dependent Material Hardening Behavior of 508 low Alloy Steel

Abstract

Chaboche-based material hardening models were used to investigate the cycle/time dependency of the elastic-plastic behavior of 508 low alloy steel (LAS), a commonly used material for light water reactor components. Strain-versus-stress curves were derived from uniaxial tensile and fatigue experiments conducted under various conditions, such as in-air at room temperature, in-air at 300 °C, and primary loop water conditions for a pressurized water reactor (PWR). These data were then used to estimate material parameters such as the elastic modulus, yield stress, and variables related to Chaboche-based linear and nonlinear kinematic hardening models. The results estimated from the fatigue test data suggest that the material behavior is highly sensitive to fatigue cycles, in addition to temperature. The authors anticipate that the findings of this research will help develop computer-based advanced modeling tools to extrapolate stress-strain evolution of reactor components under multi-axial stress states and, hence, will help predict their fatigue life more accurately.