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利用透射电镜(TEM)对氮含量为0.66%和1.2%的高氮奥氏体不锈钢的冷变形微观结构进行了对比研究。结果表明,氮含量的增加提高了材料的层错能,强烈促进位错的平面滑移。冷变形过程中不断形成机械孪晶,机械孪晶随变形量的增加而减小,在60%变形量时只有几百纳米长。运用扩展位错和短程有序理论对氮的作用机理的分析表明,氮合金化引起的短程有序是促进位错平面滑移、提高材料加工硬化能力的主要因素,低层错能引起的位错扩展也有重要作用。
The microstructures of cold-deformed high-nitrogen austenitic stainless steels with nitrogen contents of 0.66% and 1.2% were investigated by transmission electron microscopy (TEM). The results show that the increase of nitrogen content increases the stacking fault energy and strongly promotes the plane slip of dislocations. In the process of cold deformation, mechanical twins are continuously formed. The mechanical twins decrease with the increase of deformation, and only a few hundred nanometers are long at 60% deformation. The analysis of mechanism of nitrogen action using extended dislocation and short-range order theory shows that the short-range order caused by nitrogen alloying is the main factor to promote the plane slip of dislocations and improve the work hardening ability of materials. The dislocation caused by low-level faults Expansion also has an important role.