Microstructure morphology and aging characteristics of 9% Cr martensitic heat-resistant steel after service

Herein, based on the strengthening mechanism and aging mechanism of 9% Cr steel, changes in the microstructure and mechanical properties during long-term high-temperature service are analyzed. The limitations of current microstructure observation in the aging rating process and the defects of the aging evaluation system are expounded. It is proposed that the aging evaluation of 9% Cr martensitic heat-resistant steel can distinguish between the abnormal microstructure and the aging phenomenon occurring during long-term operation, and the combination of higher resolution microscopy observation such as laser confocal scanning microscopy with mechanical property tests could provide a comprehensive judgement.