| 摘要 |
A cast-iron roll for a rolling mill is made by casting an alloy into an approximately symmetrical shape so that it has a white pig iron like structure in the as cast condition, hot working the casting in the plastic condition, heat treating it and finishing the roll by machining. The alloy used in the process comprises:- <TABS:1117025/C6-C7/1> not more than 0.2% in total of the detrimental elements P, S, Cu, Sn, As, Pb, Sb, Bi and Zn the balance, apart from incidental impurities being iron. The process may produce integrally cast rolls or sleeves for fixing on axial shafts. The temperature of heat treatment prior to working and the working temperature should not exceed 1125 DEG C. and is preferably at least 50 DEG C. below the solidus line for the alloy; a temperature of 900 DEG -1125 DEG C. is suitable. After hot working (e. g. forging) the alloy is annealed at 750 DEG -850 DEG C., after an optional but preferred slow cooling step, and machined. The roll is then heated to 850 DEG -950 DEG C. quenched (air or oil) and tempered at 400 DEG -700 DEG C. The roll may be tempered further at 150 DEG -250 DEG C. to relieve any residual stresses. |
