Analysis on Crack Propagation Property of High Speed Steel Type White Cast Iron Roll in Hot Strip Rolling

Abstract

Recently high-speed steel type white cast iron roll was developed and shows high wear-resistance and are widely used in hot strip rolling. However a crack caused with rolling accident in roll surface propagate rapidly and damage a roll performance. Then the investigation for crack propagation was carried out by numerical analysis with finite-element method and crack propagation test. The results concrete as follows ; (1) Crack propagates by contact with buck-up roll by means of shear mode (mode II). (2) Ordinary thermal crack less than 1 mm in length does not propagate, but abnormal mechanical crack more 1.3 mm in length caused by rolling accident propagate even under normal rolling condition. (3) Compressive residual stress of roll is not a accelerate factor for propagation of crack.