| 摘要 |
PURPOSE:To improve the toughness of a high-chromium roll having a cavity by pouring the molten metal added with a proper amount of an inoculant based on the Si amount of core material composition to the high-chromium outer layer of the specific Cr amount and piercing a cavity. CONSTITUTION:A vertical mold 9 is constituted by a centrifugally casting mold 4 having therein an outer layer 1 of high chromium containing 13-27wt% Cr and upper, lower dies 7, 6. Molten ductile cast iron is then poured through the pouring basin 8 of the upper die 7. At this time, an inoculant 14 of Fe-Si base or the like is continuously and uniformly added at 0.1-1.0wt% based on the Si amount in the molten metal composition to the core material molten metal from the hopper 13 of the pouring basin 8. Next, strain relief heat treatment and roughing are applied to the composite roll blank material 2, after which a heater insertion hole 2' is pierced. The reason for limiting the amount of additin of the inoculant is: If it is added more than the limited amunts, the molten metal slag amount of the inoculant increases and the interposition of foreign material at the interface between the outer layer and the core material becomes likely to occur. |
