Patent ID: 9724740
Date: 2017-08-08
CPC Classifications: B21B,B22D,B32B,C22C

Claim:
1. A centrifugally cast composite roll comprising an outer layer formed by a centrifugal casting method, and an inner layer made of ductile cast iron and integrally fused to said outer layer; said outer layer being made of an Fe-based alloy comprising by mass 1.3-3.7% of C, 0.3-3% of Si, 0.1-3% of Mn, 1-7% of Cr, 1-8% of Mo, at least one element selected from the group consisting of 2.5-7% of V, 0.1-3% of Nb and 0.1-5% of W, V being indispensable, and 0.01-0.2% of B and/or 0.05-0.3% of S, the balance being substantially Fe and inevitable impurities, said outer layer having a structure containing no graphite; said inner layer comprising a core portion fused to said outer layer, and a drive-side shaft portion and a free-side shaft portion integrally extending from both ends of said core portion; and the total amount of Cr, Mo, V, Nb and W in an end portion of said drive-side shaft portion being 0.35-2% by mass, and the total amount of Cr, Mo, V, Nb and W in an end portion of said free-side shaft portion being 0.15-1.8% by mass, the former being larger than the latter by 0.2% or more by mass.