Cold rolled, ductile, high strength steel strip and sheet and method therefor
AssigneeArmco Inc.
InventorsJames A. Elias, deceased, John R. Newby, Marvin B. Pierson
Life of this patent
Estimating the term…
Abstract
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 (0.02-0.10% 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.
Claims9
Cold reduced and annealed low carbon steel strip and steel stock in substantially unrecrystallized form after annealing having a 0.2% yield strength of .Badd.[45 to 65 ksi or of].Baddend. at least 90 ksi, with an elongation in 2 inches of greater than 10% [for at least 90 ksi yield strength and greater than 25% for 45 to 65 ksi yield strength], consisting essentially of, by weight percent, from 0.02% to about 0.10% carbon, about 0.1% to about 0.9% manganese, 0.02% to about 0.18% columbium, residual phosphorus, sulfur, silicon, oxygen and nitrogen, about 0.01% to about 0.08% aluminum, and balance essentially iron except for incidental impurities, with the columbium being substantially completely combined.
[4. Strip and sheet stock as claimed in claim 1, in substantially fully recrystallized form after annealing, having a 0.2% yield strength of 45 to 65 ksi and an
- elongation in 2 inches of greater than 25%.] 5. Strip and sheet stock as claimed in claim [4] 11 , consisting essentially of from about 0.03% to about 0.05% carbon, about 0.3% to about 0.6% manganese, about 0.04% to about 0.12% columbium, about 0.006% to about 0.01% phosphorus, about 0.01% to about 0.017% sulfur, about 0.004% maximum nitrogen, about 0.03% to about 0.05% aluminum, about 0.01% maximum oxygen,
- about 0.1% maximum silicon, and balance essentially iron. 6. Strip and sheet stock as claimed in claim [1] 3 , wherein zirconium is partially substituted for columbium on a stoichiometrically
- equivalent basis. 7. Strip and sheet stock as claimed in claim 1, wherein titanium is substituted for aluminum on a stoichiometrically equivalent
- basis. 8. A coated product comprising an outer layer chosen from the group consisting of aluminum, zinc, alloys of aluminum, alloys of zinc, and terne, and an inner substrate of cold reduced and annealed steel strip and sheet stock in substantially unrecrystallized form having a 0.2% offset yield strength of at least 90 ksi and an elongation in 2 inches of greater than 10%, said sheet stock consisting essentially of, by weight percent, from 0.02% to about 0.10% carbon, about 0.1% to about 0.9% manganese, 0.02% to about 0.18% columbium, residual phosphorus, sulfur, silicon, oxygen and nitrogen, about 0.01% to about 0.08% aluminum, and balance essentially iron except for incidental impurities, with the columbium being substantially completely combined, there being
- substantially no interfacial alloy layer. 9. The product claimed in claim 8, wherein said outer layer has been applied by fluxless hot dip metallic
- coating. 10. The product claimed in claim 8, wherein said substrate consists essentially of, by weight percent, from about 0.03% to about 0.05% carbon, about 0.3% to about 0.6% manganese, about 0.04% to about 0.12% columbium, about 0.006% to about 0.010% phosphorus, about 0.01% to about 0.017% sulfur, about 0.04% maximum nitrogen, about 0.03% to about 0.05% aluminum, about 0.01% maximum oxygen, about 0.1% maximum silicon, and balance essentially iron.
Cold reduced and annealed low carbon steel strip and sheet stock in substantially fully recrystallized form after annealing, having a 0.27%, offset yield strength of 45 to 65 ksi and an elongation in 2 inches of greater than 25%, said strip and sheet stock being produced from hot rolled steel coiled at 1000.degree. to 1300.degree. F., and consisting essentially of, in weight percent, from 0.02% to about 0.10% carbon, about 0.1% to about 0.9% manganese, 0.02% to about 0.18% columbium, residual phosphorus, sulfur, silicon, oxygen and nitrogen, about 0.01% to about 0.08% aluminum, and balance essentially iron except for incidental impurities, with the columbium being substantially completely combined.
Strip and sheet stock as claimed in claim 5, wherein zirconium is partially substituted for columbium on a stoichiometrically equivalent basis.
A coated product comprising an outer layer chosen from the group consisting of aluminum, zinc, alloys of aluminum, alloys of zinc, and terne, and an inner substrate of cold reduced and annealed strip and sheet stock in substantially fully recrystallized form after annealing having a 0.2% offset yield strength of 45 to 65 ksi and an elongation in 2 inches of greater than 25%, said sheet stock being produced from hot rolled steel coiled at 1000.degree. to 1300.degree. F. and consisting essentially of, by weight percent, from 0.02% to about 0.10% carbon, about 0.1% to about 0.9% manganese, 0.02% to about 0.18% columbium, residual phosphorus, sulfur, silicon, oxygen and nitrogen, about 0.01% to about 0.08% aluminum, and balance essentially iron except for incidental impurities, with the comumbium being substantially completely combined, there being substantially no interfacial alloy layer.
Dependencies are inferred from the claim text.