EVALUATION OF DETERIORATION MECHANISMS AND ROLL LIFE OF DIFFERENT ROLL MATERIALS

Evaluation of wear loss of rolls in operation is very difficult since the rolling conditions are hard to keep under control. To solve this problem a high temperature test rig was designed. A conventional roll material was compared to a hot work tool steel. The main wear mechanisms were different. The conventional roll grade was mainly subjected to thermal fatigue as could be expected. The hot work tool steel was mainly subjected to abrasive wear, and no evidence of thermal fatigue was found. The rate of material loss was 6 times higher in the hot work tool steel, but when the deterioration caused by thermal fatigue of the cast iron is taken into consideration, the deterioration rate was of the same order in both materials. The friction between the hot steel and the roll materials were of the same order. The frictional value should be a measure of the wear rate. Since the wear mechanisms are not equal, the coefficient of friction found in the test rig is only qualitatively related to roll wear.