COOLING TREATMENT OF CONTINUOUSLY ANNEALED AND COLD ROLLED STEEL SHEET

PURPOSE:To produce the continuously annealed and cold rolled steel sheet having excellent phosphate treatability by bringing an acidic soln. contg. a soluble inorg. reducing agent into contact with a high-temp. cold rolled steel sheet right after continuous annealing. CONSTITUTION:At least one kind...

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Hauptverfasser:	SAKOTA AKITO, WAKANO SHIGERU
Format:	Patent
Sprache:	eng
Schlagworte:	CHEMISTRY GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS METALLURGY METALLURGY OF IRON MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS
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Beschreibung
Zusammenfassung:	PURPOSE:To produce the continuously annealed and cold rolled steel sheet having excellent phosphate treatability by bringing an acidic soln. contg. a soluble inorg. reducing agent into contact with a high-temp. cold rolled steel sheet right after continuous annealing. CONSTITUTION:At least one kind of the acidic soln. contg. the soluble inorg. reducing agent or an aq. soln. into which boric acid is incorporated at 0.2-20wt.% is brought into contact with the high-temp. cold rolled steel sheet right after the continuous annealing. Sulfurous acid, boron hydride compd., etc., are used as the soluble inorg. reducing agent and the use of strong oxidative acids such as sulfuric acid and nitric acid for the acidic soln. is averted. The pH of said soln. is adjusted to about 0.5-4.5. Polyhydric alcohol (ethylene glycol, etc.) may be further incorporated at 0.05-40wt.% into the aq. boric acid soln. The dissolution of the oxide film on the surface of the annealed and cold rolled steel sheet is thereby accelerated and the phosphate treatability is greatly improved.