低碳钢形变诱导铁素体相变过程中碳的扩散行为

CARBON DIFFUSION DURING DEFORMATION INDUCED FERRITE TRANSFORMATION IN A LOW CARBON STEEL

在Gleeble 1500热模拟机上对低碳钢Q235进行了热压缩实验,用电子探针分析了热变形试样微观组织中的碳浓度分布.结果表明,形变诱导铁索体晶粒中的碳含量明显过饱和.这表明在形变诱导铁素体相变过程中,碳没有发生明显的从铁素体向奥氏体扩散.从热力学的角度分析,在高于奥氏体-铁素体平衡转变温度Ae3变形,变形存储能的作用最终降低了体系相变后的自由能,使得在形变诱导铁素体相变过程中,碳无需发生从铁素体向奥氏体的扩散.

In order to investigate the carbon diffusion during the deformation induced ferrite transformation, the electron probe microanalysis technique was used to measure the carbon concentration distribution in the microstructure of the specimen which experienced a hot compression process on the thermomechanical simulator (Gleeble 1500). The measurement results indicated that the carbon concentration was significantly supersaturated in the deformation induced ferrite grains, which means that there was no carbon atoms diffusion from the ferrite to the austenite during the deformation induced ferrite transformation. According to the thermodynamics analysis, there is no need for the carbon atoms to diffuse from the ferrite to the austenite during the transformation, because the accumulated stored energy has become the unique driving force when the deformation temperature is higher than the austenite-ferrite equilibrium transformation temperature A(e3).