Process of Steel Manufacturing
Steel is one of the most preferred materials for construction, manufacturing of tools, cars and for various other applications. It is an alloy of iron and some other element such as chromium.
Steel has been manufactured since ages, but the large scale commercialization of the process began only in the 19th century. The 1850s and 1860s saw the advent of different revolutionary techniques, turned the steel-making process into a mainstream industry. The ensuing technological advancements in the injection technology as well as in the process control, has made mass production of steel easier, and an integral part of the global economy.
Ancient steel manufacturing process was carried out in bloomeries and crucibles. The Industrial Revolution brought about the development of large scale methods of producing steel.
Steelmaking involves removal of impurities such as nitrogen, silicon, phosphorus, sulphur and carbon from the sourced iron, as well as alloying other elements such as manganese, nickel, chromium, etc., to produce different grades of steel.
Modern steel industries use recycled materials as well as traditional raw materials such as iron ore, coal and limestone. Almost all the steel manufactured today uses 2 processes-basic oxygen steelmaking (BOS) and electric arc furnaces (EAF).
There are 6 basic steps in the Steel-making processes, which are as follows-
This is the first step in the manufacturing of pure steel. In this step, the raw materials like iron ore, coal and lime are melted in a blast furnace. This results in the formation of molten iron, also known as hot metal, which still contains 4-4.5% of carbon and other impurities, which makes it brittle. These have to be subsequently removed.
- Primary Steel Making
The remaining impurities are removed by either BOS or EAF methods.
In the BOS method, recycled or scrapped steel is added to the molten iron in a convertor. Oxygen is blown through the metal at high temperatures and this reduces the carbon content to about 0-1.5%.
In the EAF method, scrap steel is fed through high-power electric arcs to melt the metal and convert it into high quality steel.
The steel that is obtained at the end of this step, by either of the methods, is called raw steel.
- Secondary Steel Making
This step involves treating the raw steel in different ways to get different grades of steel. This may include addition or removal of certain elements, and/or altering the temperature and the production environment.
The final grade of steel that is desired determines the further techniques that need to be applied. These may include-
- Altering the temperature
- Ladle injection
- Removal of gasses
- Continuous Casting
In this step, the molten steel is cast into cooled moulds, causing the steel to harden. Using guided rollers, the steel is drawn out of the moulds while it is still hot and then allowed to cool and fully solidify. Next, it is cut to the desired lengths, depending on the applications-beams, slabs, billets, etc.
- Primary Forging
In primary forming, the cut steel is formed into different shapes, generally by hot rolling, which eliminates the casting defects and gives a desirable shape and surface quality. Seamless tubing, long products, flat products and various other speciality products can be obtained by this process.
- Secondary Forming
The final step is the secondary forming process, which gives the steel its finished shape and properties. Various techniques can be applied at this stage, which involve-
- Heat treatment (tempering)
- Joining (welding)
- Shaping (cold rolling)
- Coating (galvanising)
- Machining (drilling)
- Surface treatment (carburising)
JSW Steel of India and Marubeni-Itochu Steel of Japan have collaborated to create JSW MI. The vast expertise of these two steel giants strives to provide the highest quality products and services to our customers. We aim at maintaining the highest level of quality, integrity, efficiency and responsibility in all the tasks and activities that we undertake.