What is Steel?

Steel is an alloy of iron (Fe) and carbon (C). In addition to carbon, it contains various alloying elements and impurity elements (non-metallic elements that cause contamination) in different proportions. The chemical composition of the elements in steel and its internal structure give it unique properties. By adding different alloying elements in various proportions or through processes such as refining or normalization, steels with properties suited to their intended uses can be produced.

Elements like manganese (Mn), phosphorus (P), sulfur (S), and silicon (Si) are elements that come from the raw materials used in steel production and are present in controlled amounts in the steel structure. Other elements like chromium (Cr), nickel (Ni), etc., are added in the required amounts in the form of ferroalloys to provide the desired characteristics to the steel.

Steel is primarily produced in two ways: from iron ore or through scrap recycling. After the steel is produced in liquid form, it is shaped either through casting into ingots or by the continuous casting method into billets or blooms.

Special Steels are those that differ from mass-produced steels in their composition, production methods, and by having lower levels of impurities such as S (sulfur) and P (phosphorus), as well as the amount of dissolved gases. These steels are grouped according to the method of production and material requirements.

Classification of Steels:

1. By composition: carbon steel and alloy steel.
2. By production method: steels produced in electric furnaces or converters.
3. By finishing process: continuous cast steels, forged steels, etc.
4. By product form: ingot steels, bar steels, sheet steels, etc.
5. By use, production programs, and deoxidation state.

Fundamental Properties of Steel:

• Sensitivity to heat treatments: Most steels are sensitive to heat treatments. Depending on the chemical composition and the heat treatment applied, the desired properties such as hardness, mechanical properties, corrosion resistance, electrical properties, and high-temperature resistance can be achieved.
• Formability at high temperatures: When heated to the required temperatures, steels acquire properties that allow them to be formed through processes such as rolling, pressing, and forging.
• Cold formability: Suitable steels can be cold-formed through processes such as rolling and pressing.
• Machining: Steels can be processed on machine tools to obtain the desired shapes and surface finishes.
• Weldability: Suitable steels can be joined through welding processes.
• Coating and finishing: Most steels are suitable for processes such as metal coating, enameling, painting, or plastic coating.