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以新型的含铌高强细晶IF钢为研究对象,在实验室进行了热轧、冷轧以及轧后模拟连续退火试验。通过微观组织观察可以发现化学成分的改善、轧制及退火工艺的控制不仅可以使这种钢具有细小的晶粒,而且存在大量细小的析出物Nb(C、N);同时晶界附近析出物非常稀少,称之为PFZ带(晶界无析出物区),且仅存在于晶界的一侧。试验结果表明由于铌系析出物非常细小以及晶粒细化作用使试验钢具有较高强度和良好的伸长率;而PFZ带的存在,这种钢具有较低的屈服强度。与传统的IF钢相比,试验钢具有晶粒细小、屈强比低、伸长率良好且塑性应变比r值较高的特点。
Taking the new type of niobium high strength and fine grain IF steel as the research object, hot rolling, cold rolling and post-rolling simulation continuous annealing test were carried out in the laboratory. Through the microstructure observation, it can be found that the improvement of the chemical composition, the control of the rolling and annealing processes not only make the steel have fine grains, but also have a large number of fine precipitates Nb (C, N); at the same time, precipitates Very rare, called the PFZ zone (grain boundary precipitation zone), and only exists in the grain boundary side. The test results show that the test steel has higher strength and good elongation due to the very fine niobium precipitates and the grain refinement effect. However, the PFZ steel has lower yield strength in the presence of PFZ. Compared with the traditional IF steel, the test steel has the characteristics of small grains, low yield ratio, good elongation and high plastic strain ratio r value.