关键词: X20CrMoV121钢, 受热面管, 力学性能, 显微组织, 高温持久强度, 状态分析

Abstract:

In order to comprehensively understand the security situation of heating surface tube made of X20CrMoV121 steel after long-term operation in thermal power plant， the mechanical performances tests， microstructure analysis and high temperature creep rupture strength tests were carried out on final superheater tube and high temperature reheater tube in a power plant. The results show that compared with original tubes， the strength of operating tubes decreases; when the precipitation phase occurs ripening， the local lath characteristics becomes weak， substructure appears in the martensite laths， the dislocation density obviously declines; and the substructure dislocation has the trend of directional arrangement， but the high temperature creep rupture strength is still higher than the design value. From the comprehensive analysis it is concluded that although the X20CrMoV121 steel tubes have aging phenomenon in some extent after 12000-hour operation， they still can meet the requirements of safe operation under design conditions.

Key words: X20CrMoV121 steel, heating surface tube, mechanical property, microstructure, high temperature creep rupture strength, state analysis