Ratcheting behavior of pressurized-bending elbow pipe after thermal aging

Z2CND18.12N austenitic stainless steel elbow pipes were studied experimentally under reversed in-plane load of 20 kN and constant pressure of 17.5 MPa after thermal aged 1000 h and 2000 h respectively at the same thermal aging temperature of 500 centigrade degrees (degrees C). The ratcheting behaviors of pressurized elbow pipes were analyzed compared with original elbow pipe. The results indicate that the ratcheting behavior of pressurized elbow pipe is prominently affected by thermal aging. The uniaxial tensile properties of Z2CND18.12N austenitic stainless steel were also studied under the same condition of thermal aging. It is shown that yield stress of material decreases obviously with the increase of thermal aging period. Chen-Jiao-Kim (CJK) kinematic hardening model was used to evaluate the ratcheting behaviors of pressurized elbow pipes under different thermal aging periods. Simulation results are perfectly agreement with experimental data. Ratcheting shakedown boundaries of thermal aged elbow pipes were determined by CJK model.