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通过对比观察不同扩孔率双相钢的显微组织,研究了铁素体贝氏体双相钢的延伸凸缘性能与组织之间的关系。试验结果表明,当显微组织由多边形铁素体和粒状贝氏体组成时,FB双相钢能达到优异的延伸凸缘性。多边形铁素体有利于扩孔率的提高而下贝氏体和板条马氏体则有害;M-A的尺寸对延伸凸缘性影响很大,随着M-A岛尺寸的减小,扩孔率逐渐增大,当M-A岛的宽度为0.7μm时,FB双相钢的扩孔率能达到120%。
By comparing the microstructure of dual-phase steels with different hole-expanding rates, the relationship between the extended flange performance and the microstructure of duplex ferritic bainite steel was studied. The experimental results show that FB duplex steels achieve excellent stretch-flangeability when the microstructure consists of polygonal ferrite and granular bainite. Polygonal ferrite is conducive to the increase of hole expanding rate and the lower bainite and lath martensite are harmful; the size of MA greatly affects the stretch flangeability, and as the MA island size decreases, the hole expanding rate gradually Increase, when the width of MA island is 0.7μm, FB double-phase steel hole expansion rate can reach 120%.