| 摘要 |
A centrifugally cast composite roll comprising an outer layer made of cast iron having a chemical composition comprising, by mass, 2.7-3.5% of C, 1.5-2.5% of Si, 0.4-1.0% of Mn, 3.7-5.1% of Ni, 0.8-2.2% of Cr, 1.5-4.5% of Mo, 2.0-4.5% of V, and 0.5-2.0% of Nb, the balance being Fe and inevitable impurities, a mass ratio of Nb/V being 0.18-0.65, and a mass ratio of Mo/V being 0.7-2.5, and a structure comprising, by area, 15-45% of a cementite phase and 1-10% of a graphite phase, and an inner layer made of cast iron having excellent mechanical strength and metallurgically bonded to the outer layer; a usable region of the outer layer as deep as 10 mm or more from the surface containing substantially no speck-like-segregated dendrites of bainite and/or martensite having diameters of 1.5 mm or more. |
