Method for producing improved metal castings by pneumatically refining the melt
AssigneeUnion Carbide Corporation
InventorFrank S. Death
Life of this patent
Estimating the term…
Abstract
Castings of superior surface quality and internal quality can be produced by: (1) transferring the melt from the furnace into a separate refining vessel provided with submerged tuyeres, and (2) refining the melt by (a) injecting into the melt through the tuyeres an oxygen-containing gas which may contain up to 90% of a dilution gas, and (b) thereafter injecting a sparging gas into the melt through the tuyeres. Preferably, the oxygen-containing gas is surrounded by an annular stream of a protective fluid. Argon is preferred for dilution, protection as well as sparging.
Claims11
A process for producing final product castings of low alloy steel and carbon steel, said castings being characterized by superior internal and surface quality, comprising the steps of:
- (1) melting selected charge materials in a furnace,
- (2) transferring the melt from the melting furnace into a refining vessel provided with at least one submerged tuyere,
- (3) refining said melt in said refining vessel by
- (a) injecting into the melt through said tuyere(s) a mixture of oxygen and at least one dilution gas, said dilution gas functioning (i) to reduce the partial pressure of the carbon monoxide in the gas bubbles formed during decarburization of the melt, (ii) to alter the feed rate of oxygen to the melt without substantially altering the total injected gas flow rate, or (iii) both (i) and (ii), and thereafter
- (b) injecting a sparging gas into the melt through said tuyere(s), said sparging gas functioning to remove impurities from the melt by degassing, deoxidation, volatilization, or by flotation of said impurities with subsequent entrapment or reaction with the slag,
- (4) teeming the melt into a cast product mold,
- (5) permitting the melt to solidify in the mold, and
- (6) removing the casting from said mold.
Dependencies are inferred from the claim text.