| 摘要 |
The outer layer of a centrifugally cast composite shell for a roll (Group XXII) is formed from white or chilled cast iron (27% Cr; 2.50% C) or tool steel (0.44% C; 4.44% Cr; 1.75% Mo; 0.28% V.) and the inner layer of an alloy comprising Ni 12-30%; Cu 5-7%; Cr 1.25-4%, Mn 1-1.5%; Si. 1-2%, C 2.75-3.1%. After casting a composite shell with an outer layer of tool steel the shell is given a softening anneal by heating at 1650 DEG F. for four hours and then furnace cooling to 1100 DEG F. at 50 DEG F. per hour. After machining the outer layer the shell is heated to 1850 DEG F. for three hours and then air cooled to harden the outer layer to Brinell hardness 564. The hardness of the inner layer is not affected by the annealling or hardening heat treatment. Specification 594,412 [Group XXII] is referred to. |
