| 摘要 |
A composite roll which has been produced by centrifugal casting and which is for use in hot rolling, comprising (a) an outer layer made of a cast iron which has both a chemical composition that contains, by mass, 2.5 to 3.5% of C, 1.3 to 2.4% of Si, 0.2 to 1.5% of Mn, 3.5 to 5.0% of Ni, 0.8 to 1.5% of Cr, 2.5 to 5.0% of Mo, 1.8 to 4.0% of V and 0.2 to 1.5% of Nb with the balance being Fe and unavoidable impurities and that has an Nb/V mass ratio of 0.1 to 0.7 and an Mo/V mass ratio of 0.7 to 2.5 and satisfies 2.5≤V+1.2Nb≤5.5, and a structure that contains 0.3 to 10% by area of a graphite phase, (b) a shaft core part made of a ductile cast iron having a ferrite area fraction of 35% or less, and (c) an intermediate layer made of a cast iron. |
