稀土高性能耐候桥梁钢Q345qFNH的研制

Development of Rare Earth High Performance Weather Resistant Bridge Steel Q345qFNH

针对大跨度、高强度、轻量化桥梁钢的高品质要求,采用低碳、低裂纹敏感性成分设计路线和控轧控冷工艺,研制了一种新型高性能桥梁钢。添加耐候元素Cu、Cr、Ni以保证钢板耐蚀性,添加稀土Ce来进一步提高钢板的低温冲击韧性及耐蚀性。结果表明:新型桥梁钢的再结晶轧制区铸坯开轧温度为1150~1190℃,非再结晶轧制区终轧温度控制在820~870℃;钢板的冷却速率为6~10℃/s,终冷温度为630~650℃。显微组织为珠光体和铁素体,强度、塑性、冷弯及低温冲击韧性均满足标准要求。添加稀土Ce后,试验钢的平均腐蚀速率由51.8μm/a降至34.50μm/a。

Aiming at the high quality requirement of long-span, high-strength and lightweight bridge steel, a new type of high-performance bridge steel was developed by using low-carbon and low-crack-sensitivity composition design route and TMCP process. The weather resistant elements of Cu, Cr and Ni were added to ensure the corrosion resistance of the steel plate, and rare earth Ce was added to further improve the low temperature impact toughness and corrosion resistance of the steel plate. The results show that the open rolling temperature in recrystallization rolling area of the new bridge steel is1150-1190℃, the final rolling temperature in non-recrystallized rolling zone is 820-870 ℃, the cooling rate is 6-10℃/s, and the final cooling temperature is 630-650℃. The microstructure is pearlite and ferrite, and the strength, plasticity, cold bending and low temperature impact toughness all meet the standard requirements. The average corrosion rate of the test steel decreases from 51.8 μm/a to 34.50 μm/a after adding RE element Ce.