Imprinting of Dull Roll Surface Texture to Carbon Steel Strips in Temper Rolling by Dry Condition

Abstract

One of the important qualities of a cold-rolled steel sheet is the surface texture, which is obtained by imprinting a dull-roll surface texture. It is controlled by actual operation data and experiences, because the mechanism of the surface imprinting has not been clarified because of the complexity of elastic-plastic deformation of the rolled sheet in temper rolling. In this paper, surface imprinting is investigated in temper rolling as dry rolling of a 4-high rolling mill. Temper rolling experiments for as-annealed low-carbon steel strips and as-annealed high-carbon steel strips were conducted in the range of 1 to 11 % reductions. Electric-discharged dull rolls and shot-dull rolls were employed. Surface microstructures of temper rolled strips were observed directly, as well as surface textures in terms of the arithmetical mean deviation of the assessed profile (Ra), material ratio curves, and probability densities applied to compare the surface imprinting. As a result, the electric-discharged dull roll shows better surface imprinting than the shot-dull roll. The peak part of the roll surface is more easily imprinted on the steel sheet to form the valley part when the electric-discharged dull roll is used than when the shot-dull roll is used.