Weathering steel for bridge structures
Weathering steel, also known as atmospheric corrosion-resistant steel, is a low-alloy steel series between ordinary steel and stainless steel. It is made by adding small amounts of corrosion-resistant elements such as copper and nickel to ordinary carbon steel. It possesses the strength, toughness, ductility, formability, weldability, abrasion resistance, high-temperature resistance, and fatigue resistance of high-quality steel; its weather resistance is 2-8 times that of ordinary carbon steel, and its paintability is 1.5-10 times that of ordinary carbon steel. Simultaneously, it features rust resistance, extending the service life of components due to corrosion, reducing material thickness and material consumption, and saving labor and energy.
Weathering steel is mainly used in steel structures exposed to the atmosphere for extended periods, such as railways, vehicles, bridges, towers, photovoltaic systems, and highway projects. It is also used to manufacture structural components such as containers, railway vehicles, oil derricks, harbor structures, oil platforms, and containers in chemical and petroleum equipment exposed to hydrogen sulfide corrosive media.
Compared to stainless steel, weathering steel contains only trace amounts of alloying elements such as phosphorus, copper, chromium, nickel, molybdenum, niobium, vanadium, and titanium. The total amount of these alloying elements is only a few percent, unlike stainless steel which can contain over ten percent. Therefore, its price is relatively low.
Weathering steel generally employs a process route including raw material charging, smelting (converter, electric furnace - micro-alloying treatment - argon blowing - LF refining - low superheat continuous casting (feeding rare earth wire) - controlled rolling and controlled cooling, etc. During smelting, scrap steel is added to the furnace along with the raw material, and smelting is carried out using conventional processes. After tapping, deoxidizers and alloys are added, and the molten steel is treated with argon blowing before being cast. The argon-heated molten steel is then cast into slabs using a continuous casting machine. Due to the addition of rare earth elements, weathering steel is purified, and the inclusion content is greatly reduced.
Weathering steel, as a new generation of advanced steel material, has atmospheric corrosion resistance 2-5 times that of ordinary carbon steel, and its corrosion resistance becomes more prominent with longer service life. Due to its rust resistance, paint-free operation, reduced material consumption, labor saving, and energy saving characteristics, it can be applied to steel structures exposed to the atmosphere for long periods, such as buildings, vehicles, bridges, and towers. It can also be used to manufacture containers, railway vehicles, oil derricks, etc. Weathering steel is used in structural components such as harbor buildings and oil production platforms.
Development plans for the steel industry indicate a growing demand for weathering steel in my country, particularly in railway, highway, and power tower construction. In developed countries like the United States and Japan, weathering steel is already widely used. While my country's development in weathering steel started relatively late, the rapid development of the national economy has led to increased attention from relevant domestic departments. Therefore, the research and development and upgrading of weathering steel and its corrosion resistance are of significant practical importance and will also contribute to the upgrading of the steel industry's product structure.
