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Abstract

Cold rolled, recrystallization annealed, high strength steel for porcelain enameling. The steel consists essentially of at least 0.005 wt. % niobium, at least 0.02 wt. % carbon, at least 0.10 wt. % manganese, at least 0.01 wt. % aluminum, nitrogen as an impurity, the ratio of acid sol. aluminum to total nitrogen being at least 2:1, all percentages by weight and the balance being iron and unavoidable impurities, whereby the annealed steel has a yield strength of at least 21 kg/mm.sup.2 after being strained at least 8% and when heated to at least 815.degree. C. The steel is produced by hot rolling a slab to a sheet having a finishing temperature at least A.sub.r3, coiling the hot rolled sheet at a temperature at least 677.degree. C. to precipitate residual nitrogen as aluminum nitride, removing scale from the hot rolled sheet, cold rolling the descaled sheet, annealing the cold rolled sheet without decarburization at a temperature less than 721.degree. C. for sufficient time to avoid formation of iron carbides on the surfaces of the sheet and to precipitate the niobium as niobium carbide and temper rolling the annealed sheet. Niobium most preferably is in the range of 0.035-0.045 wt. %.

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