采用60Si2CrV、20CrMo等工业用钢,在贝氏体转变开始线附近进行短时间的贝氏体等温淬火,获得少量贝氏体,然后水冷,得到少量贝氏体+马氏体+残留奥氏体组织。应用QUANTA-400环扫电镜对贝氏体相变的形核进行了观察,发现贝氏体铁素体在晶界、相界面、晶内等处形核。研究了形核机制和形核时的能量变化,计算了晶核的临界尺寸、形核功,获得贝氏体临界晶核尺寸a*=16.7 nm(b=25 nm),形核功△G*=2.7×102 J.mol-1。 The use of 60Si2CrV, 20CrMo and other industrial steel, bainite transformation near the start of the line in a short bainite isothermal quenching to obtain a small amount of bainite, and then cooled to obtain a small amount of bainite + martensite + retained austenite organization. The nucleation of bainitic transformation was observed by QUANTA-400 ring-scan electron microscope. It was found that bainitic ferrite nucleated at grain boundary, interphase and intragranular. The nucleation mechanism and the energy change during nucleation are studied. The critical size and nucleation power of the nuclei are calculated. The critical nucleation size of a bainite is a = 16.7 nm (b = 25 nm) * = 2.7 × 102 J.mol-1.