Abstract: In order to meet the tensile strength Rm≥540 MPa and -40℃ V type impact energy ≥ 120 J requirements on Q420qE steel plate for bridge structure, the design with 0.05 〜0.11C and Nb-Ti microalloying is adopted. The deep desulfiirization mode, LF + RH refining and electromagnetic stirring etc processes are used to ensure the good quality of 300 mm x2010 mm cast slab by using TMCP (thermomechanical control process) technology and rolled plate stacked cooling, of developed Q420qE steel 18-26 mm plate, the yield strength is 446 -580 MPa, the tensile strength is 577 ~ 727 MPa, the elongation is 19.0% ~28.5% , and the impact absorption work at -40℃ is 129 - 287 J to meet the requirements of national standards

摘要： 为满足桥梁结构用Q420qE钢板抗拉强度Rm≥540 MPa、-40℃V型冲击功≥120 J的要求,通过采用0.05～0.11C,Nb-Ti微合金化成分设计以及深脱硫模式、LF+RH精炼和电磁搅拌等工艺,确保300 mm×2010 mm铸坯质量良好。利用TMCP（thermomechanical control process）轧制工艺,轧后堆垛缓冷,研发Q420qE钢18～26 mm板的屈服强度446～580 MPa,抗拉强度577～727 MPa,伸长率19.0%～28.5%,-40℃冲击吸收功129～287 J,各项性能指标均符合国标要求。