Improvements in or relating to a method of reduction refining of cast iron alloyed cast iron and hypereutectoid carbon and alloyed steels

摘要

A process for the production of cast iron, alloyed cast iron, and hypersentectoid and alloyed steels having short-flake or nodular graphite comprises refining a charge under a reducing slag of which the major proportion consists of one or more oxides, carbonates, or fluorides of the alkali or alkaline earth metals and one or more of carbon, silicon, or aluminium in an amount 1/2 to 1/50 of the weight of the oxides, carbonates or fluorides, the constituents being intimately mixed and pulverized to a size of at most 0.5 mm. The charge may comprise scrap cast iron, pig iron, scrap steel, and lathe turnings or chips and the slag may contain a minor proportion of alumina, silicon or magnesia. When lathe turnings or chips are included in the charge they should be mixed with slag before charging to prevent oxidation. Any type of furnace may be used and the melt is retained therein under the slag until a test sample shows the required graphite structure. The slag produced during melting may be removed and replaced by a fresh slag. The metal may be innoculated before casting by a graphitizing reagent which results in a modification of the structure shown in the test sample. The process is stated to produce a metal having a more or less constant hardness throughout its cross-section.