Mechanical Properties of Main Steel Pipeline P92 Steel in Ultra-Supercritical Unit after 50,000 h Service

Abstract

The mechanical properties of P92 steel after 50,000 h service were explored using the mechanical property tests, such as tensile test, bending test, and impact test by means of scanning electron microscopy (SEM) and energy disperse spectroscopy (EDS), etc. The results show that the strength, elongation, and plasticity of P92 steel after the 50,000 h high-temperature service meet the requirements specified in the related standards, with a certain aging embrittlement phenomenon, which is closely related to the structure aging after the service. The precipitates after the high-temperature service are mainly M₂₃C₆, Laves, and compounds of Nb, where the first two phases, which are large, present weak binding force to the matrix with embrittled grain boundary, but the dispersed fine compounds of Nb can be effectively pin the dislocations, and have outstanding solid solution strengthening effect, which is good for improving the strength, plasticity, and toughness of P92 steel.