超快冷终冷温度对桥梁钢组织性能的影响

两阶段轧制后，采用超快冷对实验钢进行冷却，研究了超快冷终冷温度对高强桥梁钢组织性能的影响.结果表明，超快冷终冷温度显著影响实验钢的组织特征，随着超快冷终冷温度的降低，实验钢的显微组织由粒状贝氏体为主逐渐演变为板条贝氏体为主，且M/A尺寸显著细化.明确了超快冷终冷温度对实验钢力学性能的影响规律，且在236℃的超快冷终冷温度条件下，实验钢的屈服强度、抗拉强度、屈强比、-40℃冲击功和延伸率分别为745MPa，961MPa，078，1665J和168%，实现了强度、韧性和塑性的平衡，同时获得了低屈强比.

Effects of UFC Final Cooling Temperature on Microstructure and Mechanical Properties of Bridge Steels

The testing steel was cooled using ultra fast cooling (UFC) after two stage hot rolling, and the effects of UFC final cooling temperatures on the microstructure and mechanical properties of the high strength bridge steel were investigated. The results showed that the microstructural characteristics of the testing steel were obviously affected by the UFC final cooling temperatures. The main part of the microstructure of the testing steel changed from the granular bainite to the lath bainite gradually and the M/A size was significantly refined with the decrease of UFC final cooling temperatures. The effects of UFC final cooling temperatures on mechanical properties of the testing steels was also revealed. For the UFC final cooling temperature of 236 °C, the yield strength, tensile strength, yield ratio, impact energy with the testing temperature of -40 °C and elongation were 745 MPa, 961 MPa, 0.78, 166.5 J and 16.8%, respectively. The balance of strength, toughness and plasticity was achieved and lower yield ratio was also gained.