GB671467A - Improvements relating to cast iron - Google Patents

Abstract

Magnesium is added to alloyed or unalloyed cast-iron, before the iron is cast, so that the casting contains 0.02-0.04 per cent Mg and substantially all the graphite is present in a more rounded and shorter form than ordinary flake graphite. After addition of Mg the melt may be inoculated and cast shortly afterwards. An example is given of the addition of Mg, and its retention in the resulting casting within the above range, to iron containing C 3.36 per cent, Si 1.8 per cent, Mn 0.39 per cent, Ni less than 0.1 per cent, S 0.008 per cent, P 0.039 per cent, Cr 0.04 per cent, Ti 0.03 per cent; Pb less than 0.002 per cent, Sn less than 0.01 per cent, V less than 0.01 per cent. Mo less than 0.1 per cent, Cu 0.07 per cent, Mg less than 0.01 per cent, Sb and Te only very faint traces. In general, Cr may be present up to 1 per cent, Mn up to say 2.5 per cent, Cu up to 3 per cent and Al and Ni may also be present. Mg may be added as metal or as an alloy, e.g. with Ni or Cu, such as one containing 2-40 per cent Mg, or in elemental form with diluents which decrease the burning of the added metal. If added as an alloy, the alloy preferably has a density approaching or even exceeding that of the molten metal. Specification 630,070 is referred to.