低碳钢形变诱导铁素体相中碳原子的扩散与稳定性研究

利用热模拟机Gleeble-3500在温度Ae3-Ar3之间对低碳钢进行了形变诱导铁素体相变的实验研究,其应力-时间曲线表明,形变诱导铁素体相变在很短时间内转变完全,碳(C)得不到充分扩散.电子探针分析表明,诱导铁素体相中C含量远高于常规铁素体中的C含量.扫描电子显微镜分析表明,由于C含量的过饱和导致诱导铁素体是一种非稳定状态的过渡相,在回火过程中,诱导铁素体相中过饱和C将扩散逸出而最终向稳态铁素体相转变,其硬度随之降低.

INVESTIGATION ON DIFFUSION OF CARBON ATOMS AND STABILITY OF DEFORMATION INDUCED FERRITE IN A LOW CARBON STEEL

A series of tests of deformation induced ferrite transformation(DIFT)in a low carbon steel was carried out by using Gleeble-3500 hot simulation machine at a temperature range of A_(e3)-A_(e3). The time-stress curve indicates that the time of transformation is so short that the diffusion of carbon atoms is not sufficient.The results of EPM show that the carbon concentration in DIF is far higher than that of conventional ferrite,and SEM observation indicates that DIF is a quasi-stable phase. Therefore,the super-saturated carbon will precipitate from DIF,resulting in a transformation of DIF to stable ferrite phase and a decrease in its Vickers-hardness during the process of tempering.