钢的中温(贝氏体)等温处理获得的上、下贝氏体和粒状组织, 都具有各自独立的C曲线；在转变初期均能获得单一的组织, 而在转变的中、后期通常可获得相邻两组织的复合体. 必须用单一组织和Arrhenius关系求相变产物的体激活能. 将体激活能、组织形貌和体自由能曲线相结合可诠释下述论点: 下或上贝氏体是碳原子扩散控制下在奥氏体中的贫碳或极贫碳区, 进行“军队型”(队列式)原子无扩散马氏体样切变相变; 而粒状组织是碳原子扩散控制下在奥氏体中的最贫碳区, 发生“平民型”(非队列式)原子无扩散界面控制相变.
Upper bainite, lower bainite and granular structure in isothermally treated steels have all themselves C curves. A single microstructure is always produced in the primary stage, whereas the nearby two-microstructure complex is usually produced in the medium or final stage of the transformation. Only a single microstructure and Arrhenius equation must be used to deduce the overall activation energy for the transformation product. A combination of overall activation energy, morphology and free energy curve can explain the bainitic transformation mechanism and granular structure formation mechanism. The former follows military atom diffusionless martensite-like shear, which occurred in carbon-depleted region controlled by carbon atom diffusion in austenite, and the latter results from civilian atom diffusionless interface control transformation, which occurred in the most carbon--depleted region controlled by carbon atom diffusion in austenite.
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