Semi-finished steels have four main classifications:
Ingots are large rough castings designed for storage and transportation. The shape usually resembles a rectangle or square with generous fillets.
Billets are semi-finished long steel products with a square cross section. This product is either rolled or continuously cast and is then transformed by rolling to obtain finished products. Billets are used for long steel products such as:
- Other structural shapes
Blooms are semi-finished long products with a square or rectangular cross section greater than 160mm. Blooms can be made by continuous casting or by rolling from an ingot. Common finish products include structural shapes/rails/rods and seamless.
Slabs are semi-finished steel products obtained by rolling ingots on a rolling mill or processed through a continuous caster and cut into various lengths. The slab has a rectangular cross section. Slabs are used for the production of heavy machinery or for hot rolling into other thinner products like:
- Sheet metal/strip metal
Flat steel products are made from Slabs, rolled and mechanized in different processes to achieve the desired final shape.
Hot Rolled Plates
Flat rectangular steel products produced from slabs, with thicknesses from 5 – 150 mm.Uses:
Plates are used in shipbuilding, in the production of pressure equipment and vessels such as boilers, as well as in engineering, construction applications and large pipelines.
Hot Rolled Coils, Sheets and Strips
Hot rolled coils are produced from slabs that are re-rolled at above re-crystallization temperature to produce a thinner sheet (between 1 and 20 mm). This long steel sheet can be bound in coil form, cut-to-length or slit into narrower strips to give it the desired shape.Uses:
Tube makers bend and weld the steel coil, sheet or strip to produce tubes for a variety of applications. Hot rolled products are also feedstock for upstream processing into higher value industrial products. They can be modified at cold rolling mills or by applying different coatings.
Cold Rolled Coils, Sheets and Strips
Cold rolled coils are produced from re-rolling hot rolled coils under heat lower than re-crystallization temperature into thicknesses down to 0.2mm. This process improves the strength of the steel up to 20%. It also improves the surface finish and permits a tighter control of tolerances.Uses:
Common uses are tube and pipe making, white goods manufacturing, cutting to length and further processing by galvanizing and coating into higher value products. Higher grades of cold rolled coils are used for automotive applications.
Pre-Painted and Galvanized Products
Hot-dip galvanizing is the process of coating steel with a thin layer of zinc by passing the metal through a bath of molten zinc. The zinc coating prevents oxidation of the protected metal, as it increases its corrosion resistance, contributing to its longevity.Uses:
Galvanized steel is widely used in applications where rust resistance is needed, and can be identified by the crystallization patterning on the surface usually called a “spangle”. Common uses for galvanized steel are roofing and walling, safety barriers, handrails, consumer appliances and automotive body parts. The galvanized steel coils and sheets can also be painted to offer further corrosion protection and provide the material different colors as various applications may require.
Merchant Bars and Profiles
Profiles and merchant bars are billet-derived structures that come in different shapes and sizes. Round bars but also squares, angles and channels all enter in this category.Uses:
Merchant bars and profiles are used in fabrication and engineering applications and can also be further processed into a wide range of steel and steel-containing structures.
Structural or heavy sections are beams and profiles of a specific cross-section, usually in the shape of an I, H, or U. The dimensions of the flanges will vary but they are generally symmetrical and of equal width.Uses:
Structural sections are used for the construction of large structures such as bridges, high-rise buildings and heavy machinery.
Reinforcing bars or “re-bars” are long round products formed from billets. They have surface deformations in the form of ridges for a very specific use.Uses:
Reinforcing bars improve mechanical anchoring and increase tensile strength when used as reinforcement in concrete structures.
Wire rod is made from steel billets in a hot rolling process to produce thin diameters that are delivered in the form of coils.Uses:
There are many uses for steel wire rod and they depend mainly on the base grade of steel and its drawability to undergo further transformation. From wire mesh and fences to fasteners and tools, to medium and high carbon steel for wire strands and cords for pre-stressed concrete.