Hot-rolled steel coils are manufactured using steel slabs as the primary raw material. The slabs are heated to approximately 1,200°C and subsequently processed through hot rolling. Due to surface oxidation generated during the high-temperature rolling process, hot-rolled steel coils exhibit a blackened surface appearance and are therefore commonly referred to as “black coils.” Variations in thickness and width are relatively greater, particularly at the leading and trailing ends of the coil. Hot-rolled steel coils represent the most fundamental form of flat-rolled steel products. When these hot-rolled coils undergo further pickling treatment, they are classified as pickled steel coils. The pickling process primarily utilizes acidic solutions such as hydrochloric acid or sulfuric acid to remove oxide scale, rust, and other surface contaminants from the steel surface, thereby producing a cleaner and smoother finish. Following the pickling process, the surface quality and appearance of the steel coils are significantly improved, while corrosion resistance and formability are also enhanced, providing a superior substrate for downstream processing applications. Subsequent products such as cold-rolled steel, coated steel, and pre-painted steel are all further processed progressively from hot-rolled steel coils.

The most widely utilized steel product, serving as the primary substrate for cold-rolled steel production. It is extensively used in the manufacture of structural steels and welded structural steels for applications such as bridges, ships, and automobiles. In addition, it is used for steel plates for pipe manufacturing, steel plates for high-pressure vessels, and hot-rolled special steels, including carbon steels for general machinery structures, alloy steels, and tool steels. Weathering steels containing specially added alloying elements are also produced from this product.