超级贝氏体钢相变的原位观察研究

摘要

To investigate the dynamic process of bainite transformation, in situ observation of bainite transformation in a 0. 42%C superbainite steel was conducted on a high temperature laser scanning confocal microscope. It is found that the bainite embryos nucleate not only in parent austenite grain, on grain boundary and previously formed bainite platelet, but also at annealing twin during bainite transformation. In addition, during the process of bainite transition, pre-formed bainite plates and later-formed bainite plates grow in different directions resulting in the impingement between them. With mutual intersection of bainite plates, an interlocked bainite microstructure would be developed finally. In situ observation investigation makes it possible that bainite nucleation and growth can be identified in real time during isothermal holding, providing efficient method for transition theory analysis.%为了探索贝氏体相变形核和长大的动态过程，利用高温激光共聚焦扫描显微镜，对一种含碳质量分数为0．42％的超级贝氏体钢进行了贝氏体相变的原位动态观察研究．结果表明：在贝氏体保温相变期间，贝氏体形核除了发生在原奥氏体晶界、晶内以及预先形成的贝氏体处，退火孪晶还引发贝氏体形核；在贝氏体长大过程中，后形成的贝氏体板条与先形成的贝氏体长大方向不同，使两者发生碰撞，从而产生“互锁”现象，形成一种互锁的贝氏体微观组织．原位观察可以研究和分析贝氏体形核和长大的动态过程，为贝氏体相变的理论研究提供了更有效的手段．