Endurance Strength and Residual Life Assessment of T23 Steel after 96000 Hours of High Temperature and High Pressure Service

Abstract

The macroscopic morphology, oxide layer characteristics, rupture strength and residual life of T23 steel after 96000 hours of service at high temperature and high pressure were analyzed. The results show that T23 steel pipe has good macroscopic appearance, without obvious abnormal features such as cracks, folds, rolling breaks, double skin, scabs, delaminations and sharp scratches. The chemical composition of different pipe sections conforms to the standard, and the structure is mainly bainite, with uniform distribution and no obvious coarse phase. There is an obvious interface between the metal substrate and the internal oxide layer, and there is an obvious wavy line at the interface. The oxide layer is relatively dense and continuous. The tensile properties at room temperature and high temperature are good. At room temperature, the yield strength exceeds 420MPa, the tensile strength exceeds 540MPa, and the elongation exceeds 19%. After 96000 hours of use, the remaining creep life of T23 split platen superheater submitted for inspection is 84000 hours, and the remaining creep life of T23 rear platen superheater submitted for inspection is 40000 hours.