Method for making ferrous metal having improved resistances to corrosion at elevated temperatures and to oxidization
AssigneeToyo Kogyo Co., Ltd.
InventorsTakao Sasame, Toshio Yagi
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Abstract
A method for making ferrous metal having highly improved resistances to corrosion and to oxidization, which comprises hot-dipping a metallic workpiece in a molten aluminum or aluminum alloy bath, primary heat-treatment of the metallic workpiece and secondary heat-treatment of the metallic workpiece. During the primary heat-treatment, an intermetallic compound layer is formed over the surface of the metallic workpiece, which is developed into an alloy layer during the secondary heat-treatment to make the alloy layer firmly secured to the base of the workpiece. The secondary heat-treatment may be omitted depending on the application of the ferrous metal processed by this method.
Claims4
A method for making ferrous metal having highly improved resistance to corrosion and oxidization, which comprises dipping a ferrous workpiece in a molten metal bath containing an aluminum alloy, which aluminum alloy contains chromium in an amount of 1 to 10 percent by weight based on the total weight of said aluminum alloy, and having a temperature of from 750.degree. to 930.degree. C, for from 30 to 300 seconds, and heating the resultant ferrous workpiece for at least 30 minutes at an elevated temperature of from 700.degree. to 930.degree. C, thereby forming an intermetallic compound layer uniformly over the surface of said ferrous workpiece, said intermetallic compound layer containing iron and aluminum as its principle components and having a surface portion containing an aluminum-chromium compound.
Dependencies are inferred from the claim text.