MANUFACTURE OF TIN-FREE STEEL EXCELLENT IN RETORT TREATMENT RESISTANCE

PURPOSE:To improve retort treatment resistance, by applying predetermined electron beams onto the surface of a chromium-coated steel sheet before being electrolytically chromated to reform water-soluble chromium oxide hydrate into a water-insoluble oxide film. CONSTITUTION:A thin steel sheet is coat...

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Hauptverfasser:	TSUGAWA SHIYUNICHI, ICHIDA TOSHIROU, OGATA HAJIME, IMANAKA KEIKO
Format:	Patent
Sprache:	eng
Schlagworte:	APPARATUS THEREFOR CHEMISTRY ELECTROFORMING ELECTROLYTIC OR ELECTROPHORETIC PROCESSES METALLURGY PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTIONOF COATINGS
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Beschreibung
Zusammenfassung:	PURPOSE:To improve retort treatment resistance, by applying predetermined electron beams onto the surface of a chromium-coated steel sheet before being electrolytically chromated to reform water-soluble chromium oxide hydrate into a water-insoluble oxide film. CONSTITUTION:A thin steel sheet is coated with metallic chromium in an amount of 50-200mg/m per one side. Said coated surface is irradiated with electron beams of 0.5-10 Mrad. Hence, water-soluble chromium oxide hydrate having a high degree of hydration existent on the surface of the steel sheet after being chromium-coated is reformed into a water-insoluble oxide film. Thereafter, electrolytical chromating is performed in an aqueous solution mainly comprising chromic anhydride, a chromate or a perchromate. Hence, the coating film of chromium oxide hydrate in an amount of 5-30mg/m is formed on the surface of said metallic chromium layer. Thus, retort treatment resistance is improved.