Hot rolling is made of slab (mainly continuous casting billet) as raw material and made of strip by roughing mill and finishing mill group after heating. From finishing the last hot steel strip mill out through laminar flow cooling to the set temperature, which consists of the winder coil, steel coil after cooling, according to the different needs of users, with different finishing line (flat, straightening, transverse or longitudinal cutting, inspection, weighing, packaging and logo, etc.) and become a steel plate, flat roll and longitudinal cutting steel strip products. To put it simply, a slab of steel is heated (like the red, hot block you see on TV), rolled through a few rounds of rolling, then trimmed and straightened into a sheet of steel. This is called hot drawing.
The hot rolled steel coil is used as raw material, after removing the oxide scale by pickling, the finished product is rolled hard coil. Due to the cold working hardening caused by continuous cold deformation, the strength and hardness of rolled hard coil increase, and the toughness and plastic index decrease, so the stamping performance will deteriorate, and can only be used for simple deformation parts. Hard roll can be used as raw material for hot-dip galvanizing plant, because hot-dip galvanizing unit is set with quenching line. Rolling hard coil weight is generally 6-13.5 tons, steel coil at room temperature, hot rolling pickling coil for continuous rolling, inner diameter of 610mm. Cold rolling is processed and rolled out on the basis of hot rolled plate rolls. Generally speaking, it is a hot rolling process of pickling and cold rolling. Cold rolling is made of hot rolled plate at room temperature, although the steel plate will be heated by rolling during the process, but it is still called cold rolling.
