Corrosion resistant steel components and method of manufacture thereof
AssigneeLucas Industries Limited
InventorsCyril Dawes, John D. Smith, Colin G. Smith
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Abstract
To impart good salt spray corrosion resistance to alloy steel components, such components are gas nitrocarburized at 550.degree. C. to 800.degree. C. to produce an epsilon layer, oxidized to produce an Fe.sub.3 O.sub.4 layer not more than 1 micrometer thick, quenched into an oil/water emulsion, degreased and then wax coated. The steel components may be surface finished after nitrocarburizing. A carburizing, carbonitriding or neutral atmosphere heat treatment may be effected prior to nitrocarburizing heat treatment with both heat treatments being effected at above the pearlite to austenite transformation temperature.
Claims28
A method of manufacturing a corrosion-resistant steel component comprising the steps of heat treating the component in a gaseous carburizing or carbonitriding atmosphere to provide a carbon rich zone at the surface, and subsequently heat treating the component in a gaseous atmosphere to form an epsilon iron carbonitride layer on the carbon rich zone.
A method of manufacturing a corrosion-resistant steel component comprising the steps of heat treating the component in a neutral atmosphere at a temperature above the pearlite-to-austenite transformation temperature of the steel and subsequently heat treating in a gaseous atmosphere at a temperature above the pearlite-to-austenite transformation temperature to produce an epsilon iron nitride of carbonitride layer on the component.
Dependencies are inferred from the claim text.