Mechanisms of Surface Deterioration of High-Ni Grain Roll for Hot Strip Rollling

摘要

Wear test was carried out by using the two disc type wear testing simulator to clarify the effects of the following factors on the surface deterioration in high alloyed grain cast irons. Namely, contact stress, microstructures, high temperature wear behavior an initiation and propagation of the surface microcrack which is generally occurring during the hot rolling were studied. The test conditions are as follows; mated speciment temperature of 850 deg C, contact stress of 200 and 250 MPa and up to 1.25 × 10~4 revolutions with slip rate of 0.4 m/s. The mechanism of the deterioration of roll surface was discussed. During the early stage of hot rolling, surface of work roll is covered with the black film evenly formed by oxidation of roll material at high temperature, followed by the banding of black film. The wear resistant carbides initially surrounded with matrix are emerged by being worn out of the matrix during successive rolling. The emerged carbides induce the sticking phenomena by the evolution of uneven friction heat, and then the particles stuck on the toll surface disappear by the successive wear during hot rolling.