hot rolling

Is the slab (mainly for continuous casting billet) as raw material, after heating by the roughing mill group and finishing mill group made of strip steel. The hot steel strip from the last mill of finish rolling is cooled to a set temperature through laminar flow, and is rolled into a steel strip roll by a coiler. The cooled steel strip roll is processed into steel plate, flat roll and slitting steel strip products through different finishing lines (leveling, straightening, cross-cutting or slitting, inspection, weighing, packaging and marking, etc.) according to different needs of users.

To put it simply, a billet is heated (that is, the red hot steel block on TV) after several rounds of rolling, then trimming and correcting into a steel plate. This is called hot rolling.

cold rolling

Hot rolled steel coil is used as raw material, and cold continuous rolling is carried out after pickling to remove oxide scale. The product is hard rolled coil. Due to cold hardening caused by continuous cold deformation, the strength and hardness of hard rolled coil are increased and the ductile plastic index is decreased. Therefore, the stamping performance will deteriorate and can only be used for simple deformed parts. The rolled hard coil can be used as the raw material of the hot-dip galvanizing plant, because the hot-dip galvanizing unit is equipped with annealing line. The weight of the rolled hard coil is generally 6 to 13.5 tons, and the steel coil is continuously rolled at room temperature. The inner diameter is 610mm.

Features: Because it has not been annealed, its hardness is very high (HRB is greater than 90), and its machining performance is extremely poor. It can only perform simple directional bending less than 90 degrees (perpendicular to the coiling direction).

To put it simply, cold rolling is processed and rolled on the basis of hot-rolled coils. Generally speaking, it is a process of hot rolling-pickling-cold rolling.

Cold rolling is processed by hot-rolled plate at room temperature, although in the process of rolling will also heat up the steel plate, it is still called cold rolling. As a result of hot rolling after continuous cold transformation and cold rolling, the mechanical properties are relatively poor, the hardness is too high. It must be annealed to restore its mechanical properties, and those without annealing are called rolled hard coils. Rolled hard rolls are generally used to make products that do not need bending and stretching.