微量碳和氮对9%Cr耐热钢中第二相析出行为的影响

Effect of Trace Amounts of Carbon and Nitrogen on Second Phase Precipitation of 9%Cr Heat-resistant Steels

采用扫描电子显微镜、透射电子显微镜和X射线衍射分析方法,研究了微量碳和氮对9%Cr铁素体/马氏体耐热钢中第二相析出行为的影响.结果表明:微量碳和氮对9%Cr铁素体/马氏体耐热钢中第二相的析出行为有显著影响;M23C6型碳化物在超低碳耐热钢中的析出量很少;随着碳含量的降低和氮含量的升高,在正火、回火处理状态下MX型纳米析出相的颗粒密度增大;在650℃长期时效过程中,超低碳的含氮钢中Fe2W型Laves相的析出受到抑制,而复杂氮化物Z-相[Cr(V,Nb)N]的形成加速.

The effect of trace amounts of carbon and nitrogen on second phase precipitation of 9Cr ferrite/martensite heat-resistant steels was studied by scanning electron microscopy,transmission electron microscopy and x-ray diffraction analysis method.Results show that trace amounts of carbon and nitrogen have obvious influence on the second phase precipitation.M_（23）C_6 carbides are rarely found in 9Cr heat-resistant steel with ultra low carbon content.Particle density of nanometer-sized MX precipitates increases with reducing carbon and rising nitrogen content in normalized-and-tempered state.During long-term aging of the ultra low carbon steel at 650（°C）,precipitation of Fe_2W-type Laves phase is inhibited,while formation of Z-phase [Cr（V,Nb）N] enhanced.