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以新型含铌高强细晶IF钢为研究对象,在实验室进行了冷轧以及轧后模拟连续退火实验.结果表明,选择合适的退火时间,晶粒变得细小、均匀,同时存在一定量的饼形晶粒.由于添加Si、Mn等固溶强化元素,增加了钢的固溶强化作用;而合金元素Nb的添加,在组织中形成了细小的碳氮化物Nb(C,N),这些碳氮化物弥散分布,通过细晶强化和沉淀析出强化增加了钢的抗拉强度,因而高强细晶IF钢的强化机制为固溶强化、细晶强化和沉淀析出强化.更值得注意的是,由于存在PFZ带(无析出物区)而使实验钢呈现高强度低屈服现象.与传统的IF钢相比,含铌高强细晶IF钢不仅具有细小的晶粒,而且具有低的屈服强度、较高的r值等良好的成型性能.
Taking the new type of niobium-containing high-strength, fine-grained IF steel as the research object, cold-rolling and post-rolling simulated continuous annealing experiments were carried out in the laboratory.The results show that the grain size becomes fine and uniform with a suitable annealing time, The grain-like grains of the cake formed by the addition of solid solution strengthening elements such as Si and Mn increased the solid solution strengthening effect of the steel. The addition of alloying elements Nb resulted in the formation of the fine carbonitrides Nb (C, N) in the structure Carbonitride dispersed distribution, through the fine grain strengthening and precipitation precipitation increases the tensile strength of steel, so the strengthening mechanism of high strength fine grain IF steel for the solid solution strengthening, fine grain strengthening and precipitation precipitation strengthening.More worth noting is that, Due to the presence of PFZ zone (no precipitate area), the experimental steel showed high strength and low yield, Compared with the traditional IF steel, the Nb-containing high strength fine grain IF steel not only has fine grains, but also has low yield strength, Higher r value and good forming performance.