GB202464A - Improvements in process of and apparatus for manufacturing malleable cast iron - Google Patents

Abstract

202,464. Kubo, M. June 27, 1922. Malleableizing. - In malleableizing cast iron by passing an electric current through the castings while in a heated condition, the castings are embedded in appropriate material, hematite in the case of whiteheart castings, iron scale, bone dust, sand, or fireclay in the case of blachheart, or are immersed in a liquid bath and heated to a temperature materially below the melting point of cast iron, e.g. 900‹ C. whilst being subjected to the current. The process may be carried out in a furnace, Fig. 1, heated electrically by a resistance unit 15, the castings being packed in hematite in a fireclay tube 11. Electrodes 14 are provided in the tube 11 for passing a current directly through the articles, the current being controlled by a variable resistance 17. Other furnaces are described in which the heating is effected by gas or oil burners. In Fig. 3, the castings 32 are suspended, in a liquid bath 38 heated by gas or oil burners 35, and the current necessary for effecting the treatment is supplied to the castings through a regulating resistance 37. In a further modification, Fig.. 4, the castings are supported on a firebrick stand 41 heated by gas or oil burners 45, and the electrodes for passing a current through the castings are temporarily welded thereto. In treating castings having thick parts, the thinner portions are annealed in the manner described and the thick parts are annealed by passing directly therethrough a sufficiently heavy current to effect the heating.