Steels may be broadly classified into:
- Plain carbon steels account for about 90% of the world’s steel production, and are produced in integrated steel plants and some in mini steel plants. Besides carbon, these steels contain some amount of manganese and, in some cases, some other alloying elements in relatively low concentrations. Plain carbon steels may be further classified into:
- Low carbon : (0–0.2% C),
- Medium carbon : (0.2–0.6% C), used for large parts, forging and automotive components
- High carbon : (0.6–1.5% C) very strong, used for springs, edged tools, and high-strength wires
- Ultra High Carbon : Approximately 1.25–2.0% C, knives, axles, and punches
- Alloy steels are those steels where alloyed with various elements like Ni, Cr, Mo, Co, etc.. Alloy steels account for about 10% of global steel production, and are almost always made in MSPs. Alloy steels may be classified into:
- Low alloy steels : up to 5% alloying elements
- Medium alloy steels : 5–10% alloying elements
- High alloy steels : above 10% alloying elements
Steel products are made from both plain carbon and alloy steel which are classified according to the shape of the final product as:
- Long steel products — bars, rounds, rails, channels, angles, shapes, sections, billets, blooms etc.
- Flat products — plates, sheets, galvanised/coated sheets, etc.
These products are manufactured by rolling and account for virtually the entire amount of bulk steel products. In addition, small quantities of special steel products (wheels, axles, gun barrels, etc.) are manufactured by forging and some others by direct casting (engine blocks, small components, etc.).