The use of not pyrophoric, powdered sponge iron in the form of a metallurgical an additive to liquid cast iron or steels

摘要

1,138,631. Casting processes; continuous casting. OFFICE NATIONAL INDUSTRIEL DE L'AZOTE. 5 Jan., 1966 [18 Jan., 1965 ; 8 July, 1965], No. 502/66. Heading B3F. [Also in Division C7] Iron or steel are, during casting, inoculated with up to 5% by weight of a powdered non- pyrophoric sponge iron containing not more than 1% by weight of non-metallic impurities, at least 77% by weight of iron, and 0-22% of oxygen exclusively in the form of ferrous oxide, the sponge iron being constituted by aggregates of elemental particles of a size between 40 and 2000 microns. A single addition is made in the case of a batch casting process, while for a continuous casting process the sponge may be added continuously; where a very low carbon steel is being treated a simultaneous addition of finely divided carbon may be made to increase the evolution of carbon monoxide. The effect of the treatment is to produce a finer, homogeneous grain structure and to remove oxidizable impurities and dissolved gases. When treating spheroidal graphite iron it is stated to be possible to obtain a ferritic matrix directly without the necessity of an annealing step subsequent to casting.