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将C含量(质量分数)分别为0.05%和0.4%的Fe-C-Mn-Si钢进行等温处理得到贝氏体组织,采用EBSD技术对奥氏体共格孪晶界上形成的贝氏体铁素体变体进行分析.结果表明,2种钢中的贝氏体铁素体与母相奥氏体均成近似K-S取向关系.奥氏体孪晶界两侧形成取向相同的变体对.此变体对形成后,孪晶界基本不再显现.晶体学分析表明,共格孪晶界两侧可能出现的变体对最多不超过3组,且这3组变体对的惯习面均与孪晶界平行,因此,贝氏体铁素体变体都将沿孪晶界生长.含C量为0.05%的Fe-C-Mn-Si钢中奥氏体孪晶界上只观察到一组贝氏体铁素体变体对的形成,这是因为C含量较低,贝氏体铁素体生长速度较快,消除了其它变体对的形核机会,先形核的变体对一旦形核就迅速覆盖整个孪晶面.而在含C量为0.4%的Fe C Mn-Si钢中,由于C含量较高,贝氏体铁素体生长速度较慢,3组变体对均有机会形核,因此,在孪晶界上可以观察到这3组变体对同时出现.
The bainite structure was obtained by isothermal treatment of Fe-C-Mn-Si steels with C content (mass fraction) of 0.05% and 0.4%, respectively. The bainite formed on austenite co- Ferrite variants were analyzed.The results show that the bainitic ferrite and parent austenite in the two kinds of steel both approximate the KS orientation relationship.The austenite twin boundaries formed on both sides of the same orientation of the variant pairs .This variant pair formed, the twin boundaries basically no longer show.Crystal analysis shows that the two sides of the coherent twin boundaries may occur on the most no more than 3 groups, and these three pairs of variants of the habit Surface parallel with the twin boundaries, therefore, bainitic ferrite variants will grow along the twin boundaries.Cu content of 0.05% of Fe-C-Mn-Si steel in austenite twin boundaries The formation of a group of bainitic ferrite variants was observed due to the lower C content and the faster growth of bainitic ferrite, which eliminated the chances of nucleation of other variant pairs, As soon as the nuclei were nucleated, the transformation rapidly covered the entire twin plane, whereas in the Fe C Mn-Si steels containing 0.4% C, the bainitic ferrite grew more slowly due to the higher C content. Three groups Variants have the opportunity to nucleate, therefore, at The twins can be observed on the three groups of these variants simultaneously.