用光学显微镜、扫描电子显微镜及X射线衍射仪对20Mn2SiVB钢在贝氏体区不同温度等温不同时间所获得的组织和形态进行了研究。试验表明,20Mn2SiVB钢在贝氏体等温转变时,首先在奥氏体晶界析出贝氏体铁素体,随着等温时间的延长,铁素体板条增多,分割奥氏体晶粒,形成贝氏体铁素体和其板条间的富碳奥氏体岛;在920℃奥氏体化,420℃贝氏体区等温不同时间后空冷所获得组织为:无碳化物贝氏体、粒状贝氏体、残留奥氏体和马氏体,各相的体积分数随着保温时间的不同有所变化。在920℃奥氏体化420℃等温5 min后,试样可获得较好的综合性能,具有一定的TRIP效应,其Rm≈1090 MPa;A≈15.4%。 The microstructure and morphology of 20Mn2SiVB steel obtained at different temperatures in bainite region at different temperatures were studied by optical microscope, scanning electron microscopy and X-ray diffraction. Experiments show that 20Mn2SiVB steel isothermal transformation of bainite, the first bainitic ferrite precipitation in the austenite grain boundaries, with the extension of isothermal time, ferrite lath increase, the division of austenite grains, the formation of Bainitic ferrite and the carbon-rich austenite islands between the laths; and austenitizing at 920 ° C., and the structures obtained after air cooling at different temperatures in the bainite region of 420 ° C. are: carbides free bainite, Granular bainite, retained austenite and martensite, the volume fraction of each phase changes with the holding time. After austenitizing at 920 ℃ for 5 min at 420 ℃, the samples obtained better comprehensive properties with a certain TRIP effect, with Rm≈1090 MPa and A≈15.4%.