Creep Fatigue Behavior and Life Prediction Including the Load History Effect Under High Temperature

Creep fatigue interaction is one of the main failure modes for high temperature pressurized equipment. In practice, the amplitude of load on structure often changes which results in the load history effect on cyclic behavior and life of material. Therefore, 316L stainless steel 1-step and 2-step creep fatigue test under high temperature was conducted, the influence of two kinds of load history on material behavior was analyzed. The results showed the first step load with different amplitude and life fraction would lead to different hardness or softness of material and affect the cyclic behavior under the second step load. There is also much difference of material behavior at the time of load change for high-low and low-high load case. A uniform nonlinear creep fatigue damage model based on “disorder” and a modified failure rule coupled with the load history effect were presented in the paper. The creep fatigue life under 2-step load at high temperature was evaluated by the damage model and the modified rule. The predicted results were in good agreement with the experimental data.