GB654537A - Improvements in, or relating to, the decarburisation of iron or iron alloy castings - Google Patents

Abstract

654,537. Decarburizing iron castings. BIRLEC, Ltd., HANCOCK, P. F., and SCHULTE, F. W. K. July 28, 1948. No. 20092. [Class 72] [Also in Group XII] In a process of annealing carbon containing iron or iron alloy castings the charge of castings in a gas tight furnace is heated to 850-1000‹C at which temperature the carbon in the castings reacts with oxygen initially present in or supplied to the furnace to form Co and Co 2 , the products of combustion are circulated and the excess vented from the furnace, the vented products being burned in a steam generating plant at or below a predetermined efficiency and the steam produced, with or without air, is introduced into the furnace out of contact with the castings so that the process is self regulating in that the atmosphere is maintained decarburizing but non- oxidizing to the castings. The efficiency of the steam plant should not exceed 17 per cent and may be controlled by varying the supply of combustion air to the vented products. Air may be superimposed on the steam supply, the flow of air being less than the amount of steam it would be necessary to supply at the end of decarburizing if no air was superimposed. The apparatus, as shown, may comprise a furnace chamber a having heating elements f and a gas seal d. The excess products of the reaction are vented through a passage i, air for combustion being supplied through a pipe m controlled by a valve o. The heat of combustion generates steam in a boiler k, which steam, with or without air from a pipe n, is led through a pipe j into the furnace. A fan g circulates the atmosphere within the furnace. Specification 585,921 is referred to.