| 摘要 |
PURPOSE:To improve the using performance, such as abrasion resistance or the like, of this kind of roll, by casting a sleeve of an outside layer of high Cr cast iron and an inside layer of graphite cast steel, and hardening only the working layer in the caliber part of the outside layer after a heat treatment. CONSTITUTION:An outside layer 7 of high Cr cast iron is formed by centrifugal casting; thereafter, an inside layer 8 of graphite cast steel is charged by centrifugal casting or static casting in the internal part thereof to cast a composite sleeve wherein both layers having a prescribed wall thickness are welded by fusion to one body is cast. After said sleeve is cooled slowly, the sleeve is subjected to a diffusion heat treatment, the granulation treatment of the inside layer and the soft annealing of the outside layer. Only the working layer 9 of a caliber part 5 which is formed beforehand by casting on the layer 7 or is formed separately by machining is thereafter subjected to a hardening treatment, whereby the hardness of the layer 9 is made to >=75Hs. |
