析出相对Nb-V-Ti微合金钢显微组织和性能的影响

Effect of Precipitation Phase on Microstructure and Properties of Nb-V-Ti Micro-Alloyed Steel

利用扫描电子显微镜（SEM）和透射电子显微镜（TEM）等仪器研究了不同Nb-V-Ti比例的微合金钢的显微组织与性能，重点研究了复合析出粒子的形貌和形成机理，并探讨了其对组织性能的影响．结果表明：在含O．15％Ti的试验钢中，同时添加少量Nb和V可以明显改善试验钢的塑性和韧性，其强度达到1200MPa级时，断后伸长率和-20℃冲击功分别为13％和102J；复合析出相大致可以分成晶粒尺寸约为100nlYl的大颗粒和晶粒尺寸约为35～50nlYl的独立复合析出的（Nb，V，Ti）C两类，实验表明后者具有更好的析出强化效果．

This paper deals with the microstructure and properties of Nb-V-Ti micro-alloyed steels with different Nb,V and Ti contents by means of SEM and TEM.It mainly investigates the morphology and formation mechanism of the diphase precipitate and explores the effect of diphase precipitate on the microstructure and properties of the steels.The results show that the simultaneous addition of Nb and V with a small dosage may remarkably improve the ductility and toughness of the steel with 0.15% Ti;and that,when the tensile strength is 1 200 MPa,the percentage elongation after fracture achieves 13% and the impact energy achieves 102 J at-20 ℃.Two types of NbV-Ti particles in the diphase precipitate are revealed.One is the large particle with a grain size of about 100 nm and the other is the( Nb,V,Ti) C particle with a grain size of about 35 ~ 50 nm.It is found that the latter is of stronger precipitation strengthening ability.