V含量对Ti-V复合微合金钢组织和力学性能的影响

利用光学显微镜(OM)、扫描电镜(SEM)、透射电镜(TEM)、电子背散射衍射(EBSD)及物理化学相分析法等技术研究了V含量对Ti-V复合微合金钢在不同卷取温度下组织和力学性能的影响。结果表明，两种Ti-V复合微合金钢在500~650℃卷取时，组织均由多边形铁素体和珠光体组成，增加V含量会抑制珠光体的形成；500~650℃区间卷取时，增加V含量使均匀延伸率和总延伸率有一定程度降低，而抗拉强度和屈服强度显著提高，卷取温度对均匀延伸率和总延伸率的影响不大，在600℃卷取时，两种实验钢的综合力学性能均达到最佳；V含量的增加使得在600℃卷取时尺寸小于10 nm的(Ti, V)C粒子数量显著增加，高钒钢的析出强化增量σ_p在183 MPa左右，其强化机制主要为沉淀强化和细晶强化，V含量是影响Ti-V复合微合金钢的沉淀强化增量和屈服强度的主要因素。

Effect of V content on microstructure and mechanical properties of Ti-V complex microalloyed steel

Using the combination of microalloying technology and controlled rolling and controlled cooling technology, the development of microalloyed high-strength steels with well-matched strength and toughness and low cost has gradually become a research hotspot, which mainly improve the properties of microalloyed steel by the soft toughness of ferrite and the precipitation strengthening of nano microalloyed carbonitride. At present, there are few reports about the effect of V content on the strength and plasticity of hot-rolled Ti-V complex microalloyed steel sheet at domestic and abroad. Therefore, the research on the microstructure and mechanical properties of hot-rolled Ti-V complex microalloyed steel sheet can provide theoretical basis and process guidance for the development and microstructure and properties control of Ti-V complex microalloyed high strength steel. Two kinds of Ti-V complex microalloyed steels with different V contents were obtained by adding Ti and V microalloying elements. Meanwhile, the effect of V content on the microstructure and mechanical properties of Ti-V microalloyed steels at different coiling temperatures were discussed by optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron backscatter diffraction (EBSD) and physicochemical phase analysis. The results showed that when the two Ti-V microalloyed steels were coiled at 500~650℃, the microstructure was composed of polygonal ferrite and pearlite, and the formation of pearlite was inhibited by increasing the V content. When coiled at 500~650℃, with the increase of V content, the uniform elongation and total elongation decreased to a certain extent, while the tensile strength and yield strength increased significantly. The coiling temperature had little effect on the uniform elongation and total elongation and the comprehensive mechanical properties of the two experimental steels were up to best when coiled at 600℃. With the increase of V content significantly increased the number of (Ti, V)C particles smaller than 10 nm in size when coiled at 600℃. The precipitation strengthening increment σ_P of high vanadium steel was about 183 MPa, and the strengthening mechanisms were mainly precipitation strengthening and fine grain strengthening. V content was the main factor affecting precipitation strengthening increment and yield strength of Ti-V complex microalloyed steel.