绿色低碳高效超高强度桥梁缆索钢用线材的研发及应用

Development and application of green low carbon high efficiency ultra high strength bridge cable steel wire rods

桥梁缆索的高强化和轻量化要求,对于缆索用钢制造提出了更高层次的要求,兴澄特钢从材料的力学性能实现原理出发,设计了2000 MPa级超高强度缆索钢的成分、组织目标及其配套的生产工艺路径。应用浇注钢水物性控制、搅拌-冷却-轻压下配合技术,降低铸坯偏析指数至0.95-1.05,基于钢种的应变-相转变及温度-相变等材料基础研究,优化盘条控制轧制,应用自主研发的在线水浴技术(XDWP-Xingcheng Direct Water Patenting),轧后890±10℃水浴至650-680℃,绿色高效地实现盘条在相变区缓慢冷却索氏体化等温韧化处理,结合优化设计的冷拉减面率位错密度控制技术,得到成分均匀、组织均匀、力学性能良好的盘条,实现盘条索氏体含量≥90%,索氏体片层间距100-150 nm,抗拉强度>2000 MPa,断面收缩率>25%。通过材料、工艺设计及生产过程优化控制,直径Φ7.0 mm 2000 MPa级超高强度桥梁缆索钢强度、抗扭转性能稳定达到大型桥梁建设要求,应用于沪苏通跨长江公铁两用斜拉大桥。

The requirements of high strength and well ductility for bridge cable steel ask the changes both on material designing and producing. Jiangyin Xingcheng(JYXC) designed the 2000 MPa class ultra-high strength bridge cable steel on compositition, microstructure and the process route. For the high quality steel wire product, the segregation index on the billet decreased to 0.95-1.05 by controlling cast liquid steel property in a narrow range as well as applying the stirring, cooling and soft reduction technologies during casting. The rolling work carried out under condition of process temperature controlled which was designed based on the theory research conclusions of strain-phase transform, temperature-phase transform, etc.. The XDWP was designed and applied to isothermal toughening to make sure the process of patenting with lower cooling speed in the temperature range(890±10 ℃ to 650-680 ℃) of material transform. The dislocation density increased and controlled by applying the designed technology of wire area reduction with cold draw process. Finally, the steel wire output with homogeneous composition & microstructure as well as well mechanical property. The wire property test shows that the sorbite ratio is larger than 90%, the sorbite lamellar spacing ranged on 100-150 nm, the tensile strength is larger than 2000 MPa and the reduction area rate is larger 25%. The Φ7.0 mm 2000 MPa class bridge cable with higher strength and well & stable anti-torsion property is satify the requirements of large-scale bridge and applied to the Shanghai-Suzhou-Nantong highway and railway cable-stayed bridge.