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利用扫描和透射电子显微镜对Super304H奥氏体耐热钢在650℃×5000 h时效处理后的组织结构进行观察与分析。结果表明Super304H奥氏体钢中存在固溶处理过程未溶解的尺寸约为2μm块状、150 nm球状NbC以及1μm圆形夹杂物,这些NbC与基体不存在特定的位向关系,时效过程析出的尺寸约为8 nm多边形状NbC则与基体存在立方取向关系;M23C6可以NbC为核心析出形成双层结构,偶尔发现在基体单独析出,M23C6与奥氏体存在立方取向关系,在奥氏体晶界析出的多边形状M23C6与基体也存在立方取向关系,而椭圆颗粒状M23C6则不存在这种关系;奥氏体基体内析出大量尺寸约为35 nm的富Cu相与基体存在共格关系,富Cu析出相对Super304H奥氏体钢强化作用主要来自共格强化效应。
The structure of Super304H austenitic heat-resistant steel after aging treatment at 650 ℃ for 5000 h was observed and analyzed by scanning and transmission electron microscopy. The results show that there is no specific orientation in the super304H austenitic steel with the size of about 2μm, 150nm spherical NbC and 1μm circular inclusions in the solution treatment, NbC with a size of about 8 nm has a cubic orientation relationship with the matrix; M23C6 can form a double-layered structure with NbC precipitated. Occasionally, it is found that there is a cubic orientation relationship between M23C6 and austenite at austenite grain boundaries There is also a cubic orientation relationship between the precipitated polygonal shape M23C6 and the matrix, while the elliptical granular M23C6 does not have this relationship. A large number of Cu-rich phases with a size of about 35 nm precipitated in the austenite matrix have a coherent relationship with the matrix, Precipitation relative to Super304H austenitic steel strengthening effect mainly from the coherent strengthening effect.