Steel
Steel is an alloy that consists of a combination of the element iron and the amount of carbon that ranges from 0.2% to 2.1%. The carbon amounts in the steel alloy play an active role in the classification of the steel. Although carbon is generally the alloying agent of iron, different elements such as magnesium, chromium, vanadium and tungsten can be used in alloying the iron element. Carbon and other elements act as hardening agents by preventing the crystal lattices in the iron atom from slipping and crossing each other. The varying amounts of alloying elements in the steel and the forms in which they are present (dissolved elements, precipitate phase) control the properties of the steel such as hardness, ductility and stress point. Although steels with high carbon content are harder and stronger than iron, they are less ductile. High-carbon alloys are known as cast iron because of their low melting points and casting capabilities. Steel is also distinguished as wrought iron, which contains small amounts of carbon but includes iron slags. Both distinctive factors increase the rust-inhibiting properties of steels and provide better weldability. The main stages of modern steel production are outlined below.
Iron Production
First of all, iron ore, coke and lime are put into the melting furnace. The resulting cast iron still contains around 4-4.5% carbon and other substances. This causes the structure to be brittle.
Primary phase
One method is to mix scrap steel into cast iron in the converter. With this method, oxygen is expelled at high temperatures. This reduces the carbon ratio to 0-1.5%. In another method, as an alternative, scrap steel is fed from an electric arc furnace (at temperatures up to 1650 ° C) and melted into high quality steel.
Secondary phase
At this stage, the desired chemical composition is achieved in the steel obtained by the methods mentioned above. This is accomplished by adding or removing certain elements with temperature and production environment changes. Depending on the steel properties required, one of the processes listed below can be applied:
Mixing, Melting in the pot, Injection in the pot, Degassing, Basic Oxygen Furnace
Primary forming
Generally, the material is formed by the rolling method. With this method, the desired shape and surface quality can be achieved by reducing casting errors. Hot rolling products can be classified as flat products, long products, seamless pipes and special products.
Production, Fabrication and Finishing
Finally, the final shape are given to steel by secondary forming processes.