| 摘要 |
PURPOSE:To prevent breakdown of a roll by bringing a solidication start temp. of the inner layer to be higher than a solidification completion temp. of the outer layer by a specific value and limiting contents of C, Si, Mn, Ni, Cr, Mo, etc., in the outer and inner layers in prescribed percentages. CONSTITUTION:Composition of the outer layer is limited to be, by wt., 2.0-3.5% C, 0.4-1.5% Si, 0.4-1.5% Mn, <=3.0% Ni, 10-22% Cr, 0.8-8.0% Mo, etc. Composition of the inner layer is limited to be, by wt., 2.6-3.5% C, 1.5-3.5% Si, 0.4-1.5% Mn, <=2.0% both Ni and Cr, <=1.0% Mo, 0.01-0.1% Mg, etc. By that contents adjustment, a solidification start temp. of the inner layer is kept higher than a solidification completion temp. of the outer layer by 120 deg.C so that generation of carbide enriched zone in the boundary between both the layers is prevented. Therefore, generation and propagation of cracks in the boundary is eliminated, so that a roll is prevented from breaking. |
