热轧低碳钒钢强韧化机制的研究

Strengthening and Toughening Mechanism of Hot-Rolled Low Carbon Vanadium Steel

采用不添加Mo,Cr,Ni,低成本V-N微合金化的成分设计,对实验钢进行控轧控冷(TMCP)实验,探讨其相变机理与析出行为,利用光学显微镜、扫描电子显微镜(SEM)、透射电子显微镜(TEM)等测试手段,系统地研究了热轧微观组织和综合力学性能.结果表明,显微组织为针状铁素体、准多边形铁素体和粒状贝氏体及少量三角状M/A岛,析出的细小V(C,N)粒子呈不规则的椭球状,较均匀弥散地分布于铁素体基体内部.实验钢的屈服和抗拉强度分别为618,701 MPa,断后延伸率19%,冷弯性能合格,扩孔率达到94%,延伸凸缘性能及低温冲击性能良好,满足轮辐用钢的加工要求.细晶强化、固溶强化、析出强化、相变强化为主要强化机制.

Composition design of lowcost V-N microalloying steel was studied without adding Mo,Cr,Ni. The thermo-mechanical control process（ TMCP） test was conducted. The phase transition mechanism and precipitation behavior were discussed. The microstructure and comprehensive mechanical properties of the hot-rolled Bainitic steel were systematically studied by optical microscopy,scanning electron microscopy（ SEM） and transmission electron microscopy（ TEM）. The results indicated that the microstructure is consisted of acicular ferrite,quasipolygonal ferrite and granular bainite and small triangular M/ A island. The fine precipitates present disks and distribute dispersedly in the ferrite matrix. The yield strength,tensile strength and elongation of the steel are 618 MPa,701 MPa and 19%,respectively. The property of cold bending is qualified,the hold-expansion ratio reaches 94%,and strentch-flangeability and the lowtemperature impact performance is good. The above results can meet the demand of the automotive wheel disc. The fine grain strengthening,solid solution strengthening,precipitation strengthening and phase transformation strengthening are the main strengthening mechanisms.