钒氮微合金化高强度球扁钢的强韧化机制

针对球扁钢在孔型轧制时球头、腹板部位组织性能不均匀的问题，研究了钒氮微合金化技术改善高强度球扁钢截面均匀性的作用机制。采用ANSYS有限元模拟了球扁钢轧后冷却温度场的分布。结果表明，球扁钢轧后冷却过程中球头心部冷却较慢，腹板冷却较快。950℃终轧后冷却150S时，球头心部、腹板温度差异约为120℃；对比分析了钒和V—N...

Strengthening and Toughening Mechanism of High Strength V-N Micro-Alloyed Bulb-Flat Steel

Microstructures and mechanical properties difference of V and V-N microalloyed bulb-flat steel was analyzed,and strengthening and toughening mechanism of experimental steel was further discussed.The results show temperature field of bulb-flat steel is nonuniform during cooling after finish rolling.The cooling rate in the center of the bulb is much higher than that in the flat.The temperature difference between center and flat is about 120 ℃ when the finish rolling temperature is 950 ℃.Yield strength of bulb-flat steel is increased significantly and strength difference between center and flat is only 5-10 MPa by using V-N microalloyed technology designing.The microstructures of experimental steel is also refined,the average ferrite grain size difference between center and flat is only 1.24 μm which improve the impact toughness of steel ultimately.The slower cooling rate promote the precipitation of V(C,N),and refining the second particles at the same time,which improve the section homogeneity caused by different cooling rate and pass deformation.