Failure analysis of a 12Cr1MoV superheater tube after 280,000 h of service

An in-depth analysis of the 12Cr1MoV superheater steam tube, which experienced failure after 280,000 h of operation, has been completed. The findings revealed that while the tube's chemical composition and room temperature hardness complied with the established standards, there was a notable reduction in its mechanical short-term properties under high temperatures. The material demonstrated significant spheroidization and carbides precipitation along the grain boundaries. Despite these microstructural changes, the tube material maintained relatively enhanced performance characteristics. The study concluded that the main factors contributing to the reduction in the tube's load-bearing ability, the initiation of cracks, and eventual fracture were the formation of creep voids and the presence of macroscopic cracks. These findings underscore the importance of considering high-temperature mechanical performance and microstructural integrity in the assessment of superheater tube longevity and reliability.