GB247735A - Improvements in or relating to the production of die-cast iron castings - Google Patents

Abstract

247,735. Walford, E. W., (Holley, E.). Feb. 10, 1925. Drawings to Specification. Casting processes.-A die-cast soft grey iron casting is made from pig-iron containing more than 2 per cent of silicon without the addition of steel scrap, the cooling rate being accelerated to an extent somewhat less than that required to produce a chilled effect, so that the carbon is precipitated rapidly and is uniformly distributed as minute particles of graphite. The iron employed may be No. 1 foundry iron containing more than 0.5 per cent of manganese and 0.05 per cent of sulphur and approximately 3.25 per cent of carbon, 2.75 per cent of silicon, and 0.2 per cent of phosphorus. It may be melted with an equal weight of scrap iron of the same quality. The resulting casting is stated to have a smooth soft workable surface and an internal structure free from hard spots. A casting made from iron containing 3.25 per cent of carbon, 2.75 per cent of silicon, and 0.6 per cent of manganese is stated to have a Brinell hardness of 200 and great tensile and compression strength, and to have more than 90 per cent of the total carbon uniformly distributed throughout the mass as graphite crystals whose major dimensions are less than one-thousandth of an inch. The castings are made in metal moulds such as described in Specification 209,043, the castings being held therein by adjustable yielding pressure and discharged therefrom while still red hot. The moulds are provided with an insulating lining, as described in Specification 202,273, and a coating of lampblack, as described in Specifications 201,913 and 204,688, to regulate the cooling rate. The moulds are heated and the first castings are rejected until the moulds reach a temperature of 900‹ F.