COLD ROLLED, DUCTILE, HIGH STRENGTH STEEL STRIP AND METHOD THEREFOR

摘要

Cold reduced, annealed steel strip and sheet stock having 0.2% yield strength of 45 to 65 ksi with an elongation of at least 25%, or having a yield strength of at least 90 ksi with an elongation of at least 10%. A low carbon steel (0.020.10% C) typical of rimmed or drawing steel analysis is preferably vacuum degassed, and 0.02% to 0.18% columbium is added. The casting is hot rolled, coiled not higher than 1300.degree.F. cold reduced 40% to 70%, and annealed at low temperature for a time sufficient to restore desired ductility without substantially decreasing yield strength.