GB972708A - Improvements relating to the manufacture of cast iron - Google Patents

Abstract

<PICT:0972708/C6-C7/1> <PICT:0972708/C6-C7/2> Cast iron to a controlled form of flake or nodular graphite structure is produced by a method wherein one or more additives, preferably having boiling-point below that of cast iron, are placed in a container 2 through which gas can pass, the container being arranged in a vessel e.g. a ladle 1 (see Fig. 1) containing molten cast iron, and an inert gas such as nitrogen, argon or helium is blown into the vessel e.g. from supply line 5 through the container 2. The container may be of refractory material coated with a graphite wash having a gas inlet member 4 and a removable top member 3 both of porous refractory material. Examples of additions are Se, Zn, K, Mg, Ba, Cd, Li, Te, Nd, Sr or their alloys; additions difficult to take in solution such as Mn, Cr, V, Si, Ca, Mo, Ce, La, Za and/or their alloys are preferably added in a modified ladle 6 (see Fig. 3) which has a cage 7 of expanded metal, e.g. steel coated with an aqueous slurry of silica flour, clay or sodium silicate, retained in position by a shelf 8 having an aperture 9 immediately above a porous member 10, e.g. of silica brick, set in the ladle lining. Examples specify the addition of alloys of Mg-Fe-Si, Fe-Mo or Fe-Mn or of magnesium granules with inert material.