服役T91钢中碳化物的萃取工艺与演变规律

Extraction technique and evolution of carbides in serviced T91 steel

通过电解萃取的方法获取了不同服役时间T91钢中的碳化物粒子,利用SEM、XRD、EDS对萃取碳化物的物相、含量、形态及成分进行了分析,讨论了T91钢中碳化物随服役时间的演变规律。研究结果表明,T91钢中碳化物主要有两种:M23C6和MC,其中M23C6占绝大多数。随着服役时间延长,碳化物会发生如下变化:尺寸上,M23C6逐渐沿晶界粗化,MC则相对稳定,运行105296 h后仍未见粗化和增多;形态上,初始的棒状碳化物逐渐开始球化;成分上,Mo、Cr、V由基体逐渐向M23C6中扩散迁移,使得碳化物中Mo、Cr、V增加,Fe含量减少。

Carbide particles in T91 steel after service for different time were obtained by electrolytic extraction method and their phase, amount, morphology and composition were analyzed by SEM, XRD and EDS. The results show that the carbides in T91 steel exist mainly in two forms： M23C6, which is the majority, and MX. With increasing service time, the M23 C6 carbides coarsen gradually along grain- boundary, while the MX carbides are relatively stable. No significant increase of size and amount of MC carbides are observed in the T91 steel even after service for 105296 hours. Morphologically, the initial rod-like carbides are spheroidized gradually. Mo, Cr, V in solid solution diffuse into M23C6, which leads to the increase of Mo, Cr, V and the decrease of Fe in the carbides as service time increases.