Wire rod for galvanized steel wire of 2100MPa bridge cable

Wire rod for galvanized steel wire of 2100MPa bridge cable

Breaking the Guinness Record in World Bridge History

With the development of technology in the bridge industry, currently all ultra long span bridges over one kilometer are suspension bridges or cable-stayed bridges. Long span suspension bridges and cable-stayed bridges are representative structures of modern bridges. The bridge cable system composed of high-strength steel wires is the main load-bearing and force transmission structure of suspension bridges and cable-stayed bridges. The main material of these cable structures is the bridge cable steel wire. The cables of large-span bridges not only bear dynamic and static loads for a long time, but also are exposed to wind, rain, humidity, and polluted air for a long time. The cable structure is prone to stress and corrosion damage and failure, as it can withstand both "load stress" and "stress fatigue", as well as "metal corrosion", "stress corrosion", and "fatigue corrosion". This poses very high requirements for the quality of steel wire rods used in bridge cables.

Since 2016, Qingdao Special Steel has gradually made breakthroughs and applications in the steel used for bridge cables with strength levels of 1960MPa and above. Among them, the ø 7mm 2000MPa galvanized steel wire strength for the cables of the Shanghai Tongjiang Highway and Railway Bridge and the Shanghe Hangzhou Wuhu Yangtze River Highway and Railway Bridge is currently the highest strength level among the world's completed and opened bridge beams.

In 2023, Qingdao Special Steel successfully developed 7.0mm 2100MPa galvanized steel wire rods for bridge cables of the Chaoma Railway Ma'anshan Highway and Railway Dual use Yangtze River Bridge. 2100MPa is the world's highest strength level in cable-stayed bridges and is currently being supplied in succession. In September of the same year, the Zhangjinggao Yangtze River Bridge, which had already started construction, set a Guinness record for the highest strength in the history of bridges in the world. The successful development of a sample of 2200MPa grade steel wire rods for cables marked that Qingdao Special Steel was at the forefront of the world in the research and development of galvanized steel wire rods for ultra-high strength bridge cables, transforming from a follower to a leader in the field of bridge cable steel.

In the field of steel for bridge cables, the wire rods produced using the Steimo air-cooled (DP) process meet the raw material requirements for 1670MPa, 1770MPa, and 1860MPa bridge cables. But as the span of the bridge increases, in order to improve safety and reduce self weight, the requirements for the strength level of bridge cable steel wires are also increasing, and thus the requirements for the raw materials used for bridge cable steel wire rods are becoming more stringent. The traditional Steimo air cooling process can no longer meet the requirements of wire rod raw materials for bridge cable steel wires of 1960MPa and above.

Qingdao Special Steel relies on its strong independent research and development capabilities to continuously break through and innovate in new product research and development, and overcome a series of "bottleneck" key technical problems. In terms of heat treatment technology, innovative reforms have been made, and the first domestic offline heat treatment production line (QWTP) and the first domestic online heat treatment production line (QMIT) have been independently designed and constructed. They are green and environmentally friendly heat treatment processes that have been proven to meet the requirements of ultra-high strength and torsional performance of bridge cable steel wires through practical testing. Through theoretical innovation and production practice of air cooling and heat treatment processes for new steel grades, the heat treated wire rods can meet the technical quality requirements of ultra-high strength bridge cable steel.