The scrap steel, rolling breakage and strip tail flail caused by rolling instability will cause different degree of damage or destruction to the roll surface. From the point of view of failure mechanism, the scrap steel is in static contact with the roll surface, or the scrap steel sheet is attached to the roll surface after rolling, and the thermal impact of high temperature strip on the roll surface will cause hot cracks. When the tail of the strip steel slaps the roll surface, the mechanical stress on the roll surface exceeds the tensile strength of the roll surface material, which will cause mechanical stress crack. 

Field experience shows that mechanical stress often causes damage to the inside of the roll surface, which is the reason why “an accident must be carried out eddy current testing after 3 subsequent service” for the roll of the frame after finishing rolling. No matter what kind of crack, for high speed steel and high nickel chromium materials of the roll, must be eliminated clean, otherwise it may lead to deeper cracks or peeling.