Steel Industry
Steel is the most critical engineering and construction material in any country. It is also known as the mother of industries. Due to its high tensile strength and cheap cost, it is used vastly in manufacturing cars, infrastructure, ships, trains, machines, and weapons. A rough estimate tells that over 20 billion tonnes of steel are in use, which is equivalent to well over two tonnes for every person on Earth. Steels are alloys of mainly iron combined with carbon and other metals and non-metals. Rarely steel alloys are also the combination of nickel, tungsten, chromium, lead. Scarcely composition of molybdenum, vanadium, zirconium, cobalt, and copper is also present in steel alloys.
Steels have the quality to be repeatedly recycled without any significant loss of performance or change in properties. Steel Manufacturing Process Methods for manufacturing steel have evolved significantly since industrial production began in the late 19th century.
Manufacturing Process
The steelmaking process starts with the dispensation of iron ore. The rock containing iron ore is extracted using magnetic rollers and is then grounded into granules. Fine-grained iron ore is processed into coarse-grained clumps for use in the blast furnace. Coal present in the ore is cleaned of impurities in a coke furnace, yielding an almost pure form of carbon. A mixture of iron ore and coal is then heated in a blast furnace to produce molten iron, or pig iron, from which steel is made. Modern methods, however, are still based on the same premise as the original Bessemer Process, which uses oxygen to lower the carbon content in iron. Steel production today uses recycled materials and traditional raw materials, such as iron ore, coal, and limestone.
Steel Making Processes
Basic oxygen steelmaking (BOS) and electric arc furnaces (EAF) account for virtually all steel production. The first step in making steel involves the raw inputs of iron rocks, coke, and lime being melted in a blast furnace. The resulting molten iron, also called hot metal, still contains 4-5% carbon and other impurities that make it fragile (c). Primary Steelmaking has two methods:
• BOS (Basic Oxygen Furnace).
The BOS method adds recycled scrap steel to the molten iron in a converter. At high temperatures, oxygen is blown through the metal, which reduces the carbon content to between 0.5-1.5%.
Manufacturing of steel by BOS process
• EAF (Electric Arc Furnace).
The EAF method feeds recycled steel scrap through high-power electric arcs with a temperature rise of up to 1,650 degrees Celsius to melt the metal and convert it into high-quality steel. In primary forming, the cast steel is then formed into various shapes, often by hot rolling. This process eliminates cast defects and achieves the required condition and surface quality. Hot rolled products are divided into flat products, long products, seamless tubes, and specialty products.
The second part in Steelmaking involves treating molten steel produced from both BOS and EAF routes to adjust the steel composition. This is done by adding or removing certain elements and manipulating the temperature. For example, adding a small percentage of chromium and Zinc-Ni alloy in steel would make it less corrosive and more stainless.
Manufacturing of steel by EOS process
Other Methods:
Depending on the types of steel required, the following secondary steelmaking processes can be used: • Rousing • Scoop furnace • Dipper injection • Degassing • CAS-OB; the process of compositional adjustment by wrapped argon sparkling with Blown Oxygen Continuous casting sees the molten steel cast into a cooled mold, causing a thin steel shell to solidify. The shell strand is withdrawn using guided rolls, then it's thoroughly cooled and solidified. Next, the strand is cut depending upon its usabilities, such as slabs for flat products (strips and plates), colorations for segments like beams, lodgings for long products such as wires or thin strips.
Finally, it's time for manufacturing, fabrication, and finishing. Secondary forming techniques give the steel its final shape and properties.
These techniques include • Shaping • Drilling • Welding • Galvanizing • Tempering • Carbonizing Throughout the process of Steelmaking; there is continuous exposure to unwanted hazards. Any mishandling or oversights can cause severe damage to a worker. There is no place for negligence being at the site of the steelmaking process.
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