贝氏体相变机制与块状转变

The Mechanism of Bainite Transformation and The Massive Transformation

应用JEM-2010高分辨电镜和Quanta-400型环境扫描电镜,运用试验与综合分析的方法,研究了纯铁的块状转变和钢中的贝氏体相变。通过对相变的形核、长大,贝氏体亚单元和组织的形成的综合研究和分析,认为贝氏体相变与块状转变存在亲缘关系。依靠随机涨落,形成贫碳区,贝氏体铁素体在贫碳的奥氏体中形核。Fe原子和替换原子通过热激活跃迁、界面扩散或切变等方式,重复产生亚单元。在亚单元边界处的富碳奥氏体中析出碳化物,或成为残留奥氏体。贝氏体相变机制具有过渡性,即切变-扩散整合机制。

By means of JEM- 2010 HREM and Quanta- 400 SEM, the massive transformation of pure iron and bainite transformation in steel were discussed by experimentation and synthesis analysis in this paper. The nucleation and growth of phase transformation,the form of bainitic sub-unites and microstructures were studied and analyzed. The results show that there is a relationship between massive transformation and bainite transformation. Carbon-poor area forms by means of random fluctuation and carbon atom diffusion. Bainitic ferrites nucleate in carbon-poor austcnite. Fe atoms and replace atoms will come into being subunit continuously at interphase and austenite by means of heat activation transition, interphase diffusion or shear mode. Cemenfite or e-carbide can turn into retained austenite separated out from carbon-rich austenite at subunit boundary. It thinks that bainite transformation have transition markedly. Diffusion-shear integrated mechanism, which is bainitic transformarion mechanism, is put forward.