Microstructure, properties and safety evaluation of low hardness P91 steel tube after long service

doi:10.13251/j.issn.0254-6051.2021.12.034

Abstract

Abstract: Microstructure, properties and safety evaluation of low hardness P91 steel after 10⁵ h service were studied by means of microstructure observation, energy dispersive spectrum (EDS) analysis, room temperature and high temperature mechanical property test, room temperature impact test and high temperature stress rupture test. The results show that the microstructure of low hardness P91 steel tube (157 HBW) after long service is composed of massive ferrite and large size M₂₃C₆ phase. Compared with the normal hardness tube, its mechanical properties at room temperature and short time mechanical properties at high temperature decrease greatly, and its extrapolation value of 10⁵ h endurance strength is 36% lower than that of the standard recommended value. The residual life of low hardness straight tube section of high-pressure steam pipe is 54 075 h, which means the operation of the power plant unit has great security risks.

Key words: P91 steel tube, long service, low hardness, high temperature rupture strength, M₂₃C₆ phase

CLC Number:

TG113.2

Deng Hui. Microstructure, properties and safety evaluation of low hardness P91 steel tube after long service[J]. Heat Treatment of Metals, 2021, 46(12): 209-213.

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