Thermal-Mechanical Fatigue Behavior of P92 T-Piece Pipe

This paper presents a study on thermal-mechanical fatigue (TMF) behavior of P92 T-piece pipe at the most critical working fluctuations. Pressure and temperature in out-of-phase (OP) and in-phase (IP) conditions were both taken into account. Cyclic plasticity model considering the effect of temperature were used, in which both effects of kinematic hardening and isotropic hardening were included. All of the parameters used in the simulation were obtained from high temperature low cycle fatigue tests (HTLCF). These parameters have been validated through the comparison of experiment data with the simulated data. Then, in order to investigate the effect of OP and IP loadings, thermal-mechanical fatigue finite element model (FEM) of P92 T-piece pipe was also developed. Simulated results reveal that at the most critical working fluctuations, the most dangerous position occurs at the region where the inner surface of horizontal pipe and branch pipe crossed for both IP and OP loadings. With the cycle increases, the equivalent plastic strain is increasing. The peak hoop stress and equivalent plastic strain at IP loading are higher than OP which indicates that IP loadings are more dangerous than OP loadings.