Nb-V复合对耐火钢力学性能的影响

Effects of niobium and vanadium on mechanical properties of fire resistant steels

对两种耐火钢在室温和600℃进行拉伸力学实验,一种不含钒元素,一种钒元素含量为0.11at%,并用透射电镜(TEM)和原子探针层析技术(APT)观察这两种耐火钢的显微组织和分析合金元素的三维空间分布。结果表明,含钒元素实验钢中为(Nb,V)C碳化物,不含钒元素实验钢中为NbC碳化物,且含钒元素实验钢中碳化物数量远远高于不含钒元素实验钢,碳化物尺寸也稍大于不含钒元素实验钢。这表明耐火钢中适当含量的钒元素可以促进碳化物的弥散析出,增强析出强化作用,提高耐火钢室温和在600℃的力学性能。

Tensile mechanical properties of V-containing and V-free fire resistant steels were investigated. Microstructure and the three- dimensional distribution of alloy elements in the two kinds of steels were analyzed by means of transmission electron microscopy （TEM） and atom probe tomography （APT）. The results show that （Nb, V）C fine carbides are precipitated in the V-containing specimen and NbC carbides are precipitated in the V-free specimen. The size and the content of （ Nb, V） C in the V-containing specimen are larger than those of NbC in the V-free specimen. The tension tests suggest that the mechanical properties of the V-containing fire resistant steel are better than those of the V-free fire resistant steel, which is attributed to the precipitation strengthening mechanism taking effect in the V- containing fire resistant steel. The addition of V element can enhance the dispersed precipitation of carbides in the steel, and therefore significantly improvs the mechanical properties of the fire resistant steels at room temperature and 600 ℃.