Answer: During the cold rolling process, the surface of the rolling bar is subjected to great extrusion and strong wear. During high-speed rolling, steel sticking and over-burning will cause cracks on the stick face. Therefore, the cold-rolled work roll should have extremely high and uniform hardness, a certain depth of hardened layer, and good wear resistance and crack resistance. Rolling has good resistance to overburning and cracking, which are the main factors for prolonging the life of rolling.

Answer: The hardness of the roll is not enough, the elastic flattening is large during rolling, and the contact area between the rolling and the strip surface increases. To obtain products with the same thickness, the rolling pressure must be increased, and the large rolling pressure is not good for the adjustment of the shape of the plate.