摘要 |
PROBLEM TO BE SOLVED: To provide an external layer material of a rolling roll in which the reduction of a thermal crown, the reduction of a drawing accident and sheet passability can be attained, fracture toughness value is high and the generation and propagation of cracks are hard to occur by solving the problem in the case where a high-speed steel material is used for the external layer material. SOLUTION: The material composing the external layer part of a roll is composed of the one contg., by weight, 1.5 to 3.0% C, 0.2 to 1.5% Si, 0.2 to 1.5% Mn, 3.0 to 8.0% Cr, 4.0 to 12.0% Mo, 4.0 to 12.0% W, 3.0 to 8.0% V, 0 to 10.0% Co, 0 to 0.5% Ti, and the balance substantial Fe, in which carbides in the structure satisfy, by area ratio, M7C3<=(M2C+M6C+MC)/10 and (M2C+M6 C)/MC>=2, and, moreover, the base is composed of >=80% bainite and <20% tempered martensite.
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