Abstract
The decrease in surface roughness of rolls in cold rolling of low carbon steel strip was investigated by using drawing-type rolling mill. From the result, the decrease in surface roughness could be reproduced as in practical cold rolling mill. The tests were performed to find the effects of the lubricants, and the materials of strip and rolls on surface roughness of rolls. The obtained results are as follows;
For the same lubrication condition, the decrease in surface roughness of rolls is more rapid in rolling Al-killed steel strip than in rolling rimmed steel strip. That would be due to the higher yield stress of Al-killed steel than that of rimmed steel. The roughness decrease is smaller in the case of paraffinic oil than in the case of octyl-stearate oil for both All-killed steel and rimmed steel. The decrease in surface roughness of rolls is smaller for rolls containing higher chromium. It has been confirmed by ISOT that the reactivity of iron oxide and iron hydroxide with stearic acid is higher than that with oleic acid. And from drawing rolling experiment, lubricant containing stearic acid shows the higher lubricity and causes larger decrease in surface roughness of rolls than that containing oleic acid. Also lubricant containing iron soap gives larger decrease in suface roughness of rolls.
Therefore, the corrosion wear mechanism plays an important role in the decrease in surface roughness of rolls in rolling of steel strip.
