1. Hot rolling

Using continuous casting slab or initial rolling slab as raw material, it is heated by a step heating furnace, phosphorus is removed by high-pressure water, and then enters the roughing mill. The roughing material is cut at the head and tail, and then enters the finishing mill for computer-controlled rolling. After final rolling, it is cooled by laminar flow (computer-controlled cooling rate) and coiled by a coiler to become a straight coil. The head and tail of straight curls are often tongue shaped or fish tail shaped, with poor accuracy in thickness and width, and often have defects such as wavy, folded, and tower shaped edges. Its coil weight is relatively heavy, and the inner diameter of the steel coil is 760mm. (Generally used in the pipe manufacturing industry.) After the straight coil is processed by cutting the head, tail, edge, and multiple passes of straightening, leveling, and other finishing lines, it is then cut or rewound into products such as hot-rolled steel plates, flat hot-rolled steel coils, longitudinal cutting strips, etc. If the hot-rolled finished coil is acid washed to remove the oxide skin and coated with oil, it becomes hot-rolled acid washed plate coil.

2. Cold rolling

Using hot-rolled steel coils as raw materials, after acid washing to remove oxide skin, cold rolling is carried out, and the finished product is rolled hard coil. Due to continuous cold deformation, the cold work hardening caused by cold deformation increases the strength and hardness of the rolled hard coil, reduces the toughness and plasticity index, and deteriorates the stamping performance. It can only be used for parts with simple deformation. Rolled hard coils can be used as raw materials for hot-dip galvanizing plants, as hot-dip galvanizing units are equipped with annealing wires. The weight of the rolled hard coil is generally 6-13.5 tons, and the inner diameter of the steel coil is 610mm. Generally, cold-rolled plates and coils should undergo continuous annealing (CAPL unit) or bell furnace annealing treatment to eliminate cold work hardening and rolling stress, and achieve the mechanical performance indicators specified in the standard. The surface quality, appearance, and dimensional accuracy of cold-rolled steel plates are superior to those of hot-rolled plates.