长时服役超超临界机组Super304H钢组织与性能

Microstructure and Properties of Super304H Steel Used in Ultra Supercritical Unit after Long-term Service

采用X射线衍射仪、光学显微镜、扫描电镜和能谱仪、万能材料试验机研究了服役42000 h后超超临界机组用Super304H钢的微观组织与拉伸性能。结果表明:经高温服役后Super304H钢在奥氏体基体晶界处和晶粒内部形成大量析出相,包括M_(23)C_6、MX和富铜相。受热力学驱动和生长动力学特性影响,Super304H钢高温服役过程中形成的析出相表现出不同的形态、尺寸和分布特征。高温服役后的Super304H钢具有较高的强度,但塑性下降。

X-ray diffractometer, optical microscopy, scanning electron microscopy, energy dispersive spectroscope and universal material testing machine were used to investigate the microstructure and tensile properties of Super304H steel serving for 42000 h in ultra supercritical unit. The results show that the precipitates including M23C67 MX and copper-rich phase appear in the austenitic matrix along the grain boundary and inside the grain for Super304H steel after high temperature service. Driven by the thermodynamic force and influenced by the growth kinetics, the precipitates forming during high temperature service exhibit different morphologies, sizes and distribution characteristics. Super304 steel after high temperature service has high strength, but the ductility decreases.