| 摘要 |
PROBLEM TO BE SOLVED: To secure the high wear resistance of a graphite-crystallized high speed steel type cast iron material used for an outer layer material of a composite roll for rolling and also to improve its surface roughing resistance. SOLUTION: The high speed steel type cast iron material has a composition consisting of, by weight, 1.8-3.6% C, 1.0-3.5% Si, 0.1-2.0% Mn, 2.0-10.0% Gr, 0.1-10.0% Mo, 0.1-10.0% W, 1.5-10.0%, in total, of either or both of V and Nb, 0.21-2.0%, in total, of at least one kind among lanthanoide series elements, and the balance Fe with inevitable impurities. If necessary, this cast iron material can contain, other than the above alloy components, 0.5-10.0% Co, and/or one or >=2 kinds among 0.01-0.50% Al, 0.01-0.50% Ti, and 0.01-0.50% Zr, and/or 0.01-0.50% B. Moreover, the graphite, crystallizing out in the structure, has <=about 10μm average grain size and about 0.1-7% area ratio.
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