Steel

Steel Composition and Properties: Steel contains 0.02% to 2.14% carbon by weight. Alloy steel includes intentional alloying elements like manganese, nickel, and chromium. Steel has improved strength and fracture resistance compared to iron. Various elements like chromium and nickel are added to modify steel’s properties. Steel can be heattreated to enhance its properties. Pure iron exists in BCC alpha iron structure at room temperature. Carbon can form cementite when it moves out of solution with iron. Different metallurgical structures form in steel based on carbon and iron concentrations. Steel density ranges between 7,750 and 8,050kg/m^3 or 7.75 and 8.05g/cm^3. Heat treating processes for steel include annealing, quenching, and tempering. Steel Production and Recycling: Iron is commonly found in the Earth’s crust as an ore. Iron is extracted through smelting, where oxygen is removed. Impurities are removed from pig iron to produce steel. Steel production involves reducing carbon content in smelted iron. Various elements are added to steel to achieve desired properties. Steel is one of the most recycled materials globally. In the United States in 2008, over 82,000,000 metric tons of steel were recycled, with an overall rate of 83%. Recycled raw materials account for about 40% of the total steel produced. Steel production exceeds the amount that is scrapped. Steel’s recyclability contributes to its sustainability. Historical Evolution of Steel: Steel production dates back to antiquity with bloomeries and crucibles. Steel was produced in Celtic Europe from 800BC and in Britain from 490375BC. Highcarbon steel was produced in the Netherlands from the 2nd4th centuries AD. Evidence of early high carbon steel production in South Asia. Wootz steel known for its durability and global exportation. Introduction of Henry Bessemer’s steelmaking process in 1855. Development of the GilchristThomas process to remove phosphorus. SiemensMartin process as a complement to the Bessemer process. Use of electric arc furnaces (EAF) for reprocessing scrap metal and pig iron into new steel. Bethlehem Steel in Pennsylvania was one of the world’s largest steel manufacturers before closing in 2003. Steel Industry and Global Impact: The steel industry contributes 8% of global greenhouse gas emissions. Major steel producers include ArcelorMittal, Tata Steel, Baosteel Group. Increase in global steel demand due to economic growth in China and India. Steel is one of the most commonly manufactured materials worldwide. China is the top steel producer with onethird of the world share. Ranking of other major steel producers like Japan, Russia, and the United States. Significant carbon dioxide emissions associated with steel production. Downturn in the steel industry at the end of 2008. Global greenhouse gas emissions attributed to the steel industry in 2021. Types of Steel and Applications: Stainless steel contains at least 11% chromium for corrosion resistance. Carbon steel makes up 90% of steel production. High strength low alloy steel provides additional strength at a modest price increase. Advanced High Strength Steel (AHSS) is a new variety meeting CAFE regulations. Stainless steels resist corrosion with added elements like chromium and vanadium. Tool steels are alloyed for maximum solution hardening. Steel is widely used in construction, infrastructure, appliances, and buildings. Major structures like stadiums and skyscrapers are supported by steel skeletons. Steel is used in car bodies, shipbuilding, aerospace, and white goods. Applications include reinforcing concrete, mining, and office furniture.