GB564679A - Improvements relating to gray iron castings - Google Patents

Abstract

564,679. Alloys. MOND NICKEL CO., Ltd. Aug. 7, 1943, No. 12788. Convention date, Aug. 7, 1942. Drawings to Specification. [Class 82 (i)] Gray iron castings'having improved resistance to growth are made from nickel-chromium cast iron in which the ranges of the respective elements are adjusted, particularly having regard to the cross-sectional thickness of the casting, and silicon is added to the melt just before pouring in order to increase the proportion of graphitic carbon and so prevent the iron from being white or mottled, and so unmachinable, brittle, and susceptible to cracking when suddenly heated or cooled. The iron contains 2.9-3.3 per cent carbon, 1.5-4 per cent nickel, 0.9-1.3 per cent chromium and 1.35-2.1 per cent silicon. The amount of silicon added shortly before casting may be 0.25-1 per cent, but is preferably 0.5-0.75 per cent by weight of the molten metal. The nickel content preferably does not exceed 2 per cent. The metal may include 1 per cent, but preferably 0.6-0.9 per cent, manganese. Sulphur not exceeding 0.15 per cent may be present, and also phosphorus, normally below 0.25 per cent, but for certain purposes, e.g. some cast stove plates, from 0.6-1.0 phosphorus may be advantageous. The iron is particularly applicable to fire-box parts, such as those used in sintering machines, and may also be used for furnace pots, furnace ring sections, gas-producer ring sections, grates and grate bars, exhaust manifolds, piston rings of Diesel engines, and cylinder liners.