Evaluation of Subsurface Fatigue Damage in Strip Mill Rolls by an X-ray Diffraction Method

概要

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The X-ray diffraction line profile analysis technique has been applied to the study of fatigue damage below the surface of the work and the backup rolls of a cold strip mill, and the backup rolls of a hot strip mill. Half value breadth has been taken as a measure of fatiguing.The fatigued zone below the surface of the rolls correlated well with the half contact length, L, being 0.03L in the work roll of cold strip mill and 0.1L in the other rolls. Changes in the half value breadth with an increase in the number of cycles of roll contact differ according to the surface hardness of the roll: continued cycling results in a decrease in the half value breadth at the surface in hard rolls (Hs≥60), and an increase in soft rolls (Hs≤50). This technique, the X-ray study of fatigue, can be extended to the prediction and prevention of accidental failure of rolls due to fatigue fracture such as spalling. Furthermore, the amount of surface dressing at regular maintenance of rolls can be saved significantly on the basis of an accurate evaluation of the depth of the fatigue damaged zone.
The Iron and Steel Institute of Japanの論文