When the roughness of the roll is low, the roll is not replaced in time. The first and second pass hard scratches are controlled as follows. 1. First of all, increase the tension of the strip outlet and reduce the tension of the strip inlet. 2. When starting the rolling mill, the pressing thickness should not be too thin, but should be pressed slowly to the set thickness. 3. Do not directly reduce the speed when reducing the speed, so as to avoid thickness fluctuations. Excessive deformation in places with thin thickness fluctuations may cause scratches. 4. If there are slippery stripes on the surface of the strip during rolling, change the thickness of the outlet in time to reduce the amount of deformation. Change the roll after this pass.