Thermal Scratch on Surface of SUS430 Stainless Steel Strip in Cold Rolling Process

The thermal scratch significantly influences the surface quality of the stainless steel in cold strip rolling. The thermal scratch has a close relation to the rolling parameters, the rolls surface and the emulsions used in rolling. In order to explain the thermal scratch on the strip surface, the cold rolling process of SUS430 stainless steel strip was investigated in the laboratory. The thermal scratch defect occurs frequently in the second rolling pass (maximum reduction in height is 32.3%), especially on the lower surface of strips. When concentration and temperature of the emulsion are the same, the thermal scratch on the surface of the strip is aggravated with increasing the roll surface roughness. With the same roll surface roughness and emulsion concentration, the thermal scratch is obviously more severe at an emulsion temperature of 63 °C than 55 °C. With the same roll surface roughness and emulsion temperature, the thermal scratch is distinctly weaker at the emulsion concentration of 6% than that of 3%.