A strip with a new crystalline structure is changed by recrystallization in the annealing process. The annealed strip is almost completely soft, so it is not suitable for processing. As long as the strip is slightly pressed, the surface of the strip will produce tensile strain and irregular slip lines, which obviously affect the appearance. The annealed strip can not be supplied to users directly, but must be rolled flat, that is, the material and shape of the plate must be improved by mild cold rolling.

The purpose of flat rolling is to eliminate the yield platform of the material and prevent the tensile strain during processing. Improve the yield limit, reduce the yield limit, and expand the plastic processing range; To obtain the desired roughness and gloss on the strip surface; Correct sheet shape.

Type of mill

After cold rolled and annealed, the surface of strip steel will be more or less sticky with some dirt, mainly composed of iron, iron ion and carbon, which will pollute the environment when it is dry and smooth. With the different degree of adhesion, when the dry leveling of these dirt will stain the work roll. Usually, they adhere to the end of the work roll, and stick to the surface of the roughing roll in the form of points or convex spots. The work roll adhered to dirt during leveling will leave periodic indentation on the edge of the strip, which will eventually lead to the reduction of the strip quality.