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12Cr马氏体耐热钢是发电及其它行业高温高压部件的关键用材。在高温高压环境下长期服役会导致材料的性能下降和组织结构退化。评价服役材料的可靠性一直是高度关注的实际问题。本文通过对发电锅炉X20再热器炉管在不同服役时期的性能和组织结构比较研究,材料硬度随寿命减损而下降,尤其是晶界硬度低于基体硬度。相应的微观结构出现碳化物粗化和蠕变损伤现象。定量分析显示,主要碳化物M23C6成分显示出明显的合金元素富集,粗化的M23C6碳化物中Cr/Fe原子比随服役时间的变化规律存在明确的动力学规律。
12Cr martensitic heat-resistant steel is the key material for power generation and other high-temperature and high-pressure components in the industry. Long-term service under high-temperature and high-pressure environment will lead to the performance degradation and structural deterioration of materials. Assessing the reliability of service materials has always been a real concern of great concern. In this paper, by comparing the performance and microstructure of X20 reheater tubes of power generation boiler in different service periods, the hardness of the materials decreases with the loss of life expectancy, especially the grain boundary hardness is lower than the hardness of the matrix. The corresponding microstructure appears carbide roughening and creep damage phenomenon. Quantitative analysis shows that the major carbides M23C6 components show obvious alloying element enrichment. There is a clear kinetic law of the atomic ratio of Cr / Fe in the roughened M23C6 carbides with service time.