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以添加稀土的20MnCrNi2Mo铸钢为研究对象,采用L78 RITA淬火热膨胀仪测定了其连续冷却转变(CCT)曲线,为制定合适的贝氏体转变工艺提供依据。采用激光扫描共聚焦显微镜(LSCM),并配以高温热台,对试验钢贝氏体形核-长大过程进行原位观察。结果表明,添加稀土20MnCrNi2Mo铸钢的贝氏体铁素体优先在晶界形核,也可以在晶内形核;贝氏体铁素体片可以向晶内生长,也可侧向激发形核长大,最终生长为不同形貌的贝氏体。贝氏体形核区域具有多样性,生长过程呈现复杂性。
Taking 20MnCrNi2Mo cast steel containing rare earth as the research object, the continuous cooling transformation (CCT) curve was measured by L78 RITA quenching dilatometer to provide the basis for making proper bainite transformation process. Laser scanning confocal microscopy (LSCM) was used with high temperature hot stage to observe in situ the nucleation and growth of bainite in test steel. The results show that the bainitic ferrite added with rare earth 20MnCrNi2Mo cast steel preferentially nucleates in the grain boundaries and can nucleate in the grain. The bainitic ferrite sheet can grow into the grains and also activate the nuclei laterally Grow up and eventually grow into different shapes of bainite. Bainitic nuclei are diverse and the growth process presents complexity.