利用淬火热膨胀仪测定了P92钢的临界点和不同等温温度下的过冷奥氏体等温转变曲线; 采用共聚焦显微镜、扫描电镜对不同等温温度下的转变组织进行观察及分析, 得到P92钢的TTT图。结果表明: P92钢的TTT图中不只有高温时的珠光体转变区, 还有Ms点附近的贝氏体转变区; 珠光体组织为粒状、纤维状或四棱柱状, 上贝氏体由片状贝氏体铁素体亚单元构成, 下贝氏体组织为片状的贝氏体铁素体上分布着点状碳化物。

Critical points and isothermal transformation diagrams of P92 steel at different temperatures were measured by quenching thermal expansion instrument, and then, isothermal transformation microstructure at different temperatures were observed and analyzed by confocal laser scanning microscopy and scanning electron microscopy; at last, the time-temperature-transformation (TTT) diagram of P92 steel was obtained. The results show that the TTT diagram of P92 steel had not only pearlite transformation zone in high temperature zone, but also bainite transformation zone near Ms point. The pearlite was granular and fibrous or quadrangular shapes, the upper bainite was composed of lamellar bainitic ferrite subunit, and the lower bainite was flaky bainitic ferrite with point-like distributed carbides.