Flat Steel Products
Flat products include plates, hot-rolled strip and sheets, and cold-rolled strip and sheets; all have a great variety of surface conditions. They are rolled from slabs, which are considered a semi finished product and are normally not sold. Provided by either a continuous caster or rolled from ingots by a slabbing mill, slabs are 50 to 250 millimeters thick, 0.6 to 2.6 meters wide, and up to 12 meters long (that is, 2 to 10 inches thick, 24 to 104 inches wide, and up to 40 feet long).
Plates are hot-rolled either from slabs or directly from ingots. Maximum dimensions vary with available slab sizes or ingot weights and with the sizes of installed rolling mills and auxiliary equipment. Thickness can be as low as 5 millimeters, but it is usually heavier (e.g., 25 millimeters) and can go as high as 200 millimeters.
The width of plates is usually between 1.5 to 3.5 meters, but there are plants that can roll plates up to 5.5 meters wide. The maximum plate length that the largest mills can produce is 35 meters. Plates are usually made in small quantities and to a customer’s specification, with different dimensions and tolerances for flatness, profile, straightness, and other properties. The edges can be ordered in either as-rolled condition or sheared, machined, or gas-cut. Plates are also sometimes cladded with corrosion-resistant sheets.
Hot-rolled strip is often shipped directly from the hot-strip mill in a large coil weighing 10 to 35 tons. Its thickness is 1.5 to 12 millimeters, and its width, depending on the available mill, is 0.7 to 2 meters. Frequently, the large coils are slit into narrower coils or edge trimmed, or they are cut to length into sheets at the finishing section of a steel plant or at a service centre. Coils and sheets are shipped either with the hot-rolled surface or with the scale removed and the surface oiled.
Cold-rolled strip, produced from hot-rolled strip, is 0.1 to 2 millimeters thick and also up to 2 meters wide, depending on a shop’s facilities. Steel plants supply this product in coils or sheets, the latter being cut on special shear lines. Cold-rolled products are available in a great variety of surface conditions, often with a specific roughness, electrolytically cleaned, chemically treated, oiled, or coated with metals such as zinc, tin, chromium, and aluminum or with organic substances.
They are usually produced to strict dimensional tolerances in order to assure efficient performance in the highly demanding operations of automated consumer-products industries.
