2009 Volume 49 Issue 6 Pages 874-880
The surface roughness of a roll is imprinted on a carbon steel sheet by temper rolling. It is important to reduce roll microwear; since the roll surface causes microwear, the roughness of the rolled sheet could not be controlled. In most cases, temper rolling is performed using lubricants or under a dry condition. However, the influence of lubricant on roll microwear has not been clarified. In this study, roll microwear has been evaluated under three lubrication states, using a 4-high rolling mill. Temper rolling experiments for as-annealed low-carbon steel strips and as-annealed high-carbon steel strips have been conducted in the reduction range of 1 to 3%. The experiments were performed under three lubrication states: a dry condition, with a water-soluble lubricant, and with a mineral oil. A shot-dull roll (SD roll) and an electric-discharged dull roll (ED roll) were employed. Surface textures of the rolls have been observed directly with a laser microscope by identifying the exact locations using markers to acquire three-dimensional microgeometry before and after rolling. Surface textures in terms of the mean surface roughness (Ra), three-dimensional texture, cross-sectional profile and material ratio curve were applied to compare the microwear of dull rolls. As a result, roll microwear was found to occur when a total contact length between roll and strip reaches 80 m. The ED roll shows greater roll microwear than the SD roll under the dry condition. The use of the water-soluble lubricant and the mineral oil decreases the roll microwear of the ED roll.