A high-strength steel sheet with excellent formability and high yield ratio that has TS of 590 MPa or more and YR of 68% or more is obtained by providing a predetermined chemical composition and a steel microstructure that contains, in area ratio, 35 to 80% of polygonal ferrite, 5% or more of non-recrystallized ferrite, and 5 to 25% of martensite, and that contains, in volume fraction, 8% or more of retained austenite, in which the polygonal ferrite has a mean grain size of 6 μm or less, the martensite has a mean grain size of 3 μm or less, the retained austenite has a mean grain size of 3 μm or less, and a value obtained by dividing an Mn content in the retained austenite (in mass %) by an Mn content in the polygonal ferrite (in mass %) equals 2.0 or more.

The present invention relates to a high-strength steel sheet and, more specifically, to a dual-phase steel sheet having excellent formability, so as to be appropriately applied to vehicle panels and the like, and a manufacturing method therefor.

This relates to a process for manufacturing a recovery annealed coated steel substrate for packaging applications and a packaging steel product produced thereby.

Ferritic stainless steel is characterized by including, by mass %: Cr: 12.0% to 16.0%; C: 0.020% or less; Si: 2.50% or less; Mn: 1.00% or less; P: 0.050% or less; S: 0.0030% or less; Al: 2.50% or less; N: 0.030% or less; Nb: 0.001% to 1.00%; one or more of B: 0.0200% or less, Sn: 0.20% or less, Ga: 0.0200% or less, Mg: 0.0200% or less, and Ca: 0.0100% or less; and a balance consisting of Fe and impurities, in which Expression (1) is satisfied.
10(B+Ga)+Sn+Mg+Ca>0.020  (1)

A high strength low alloy steel. The high strength low alloy steel strip, sheet or blank, coated with zinc or a zinc alloy, has the following composition in weight %: C: 0.03-0.07, Mn: 0.70-1.60, Si: ≦0.2, Al: 0.005-0.1, Cr: ≦0.1, Cu: ≦0.2, N: ≦0.008, P: ≦0.03, S: ≦0.025, O: ≦0.01, Ti: 0.02-0.07, V: 0.04-0.15 Mo: ≦0.03, Nb: ≦0.03, Ca: ≦0.05, the remainder being iron and unavoidable impurities,
wherein the steel strip, sheet or blank has a yield strength Rp0,2 of at least 420 MPa.

A high-strength galvanized steel sheet comprising a cold-rolled steel sheet, an intermetallic compound formed on the cold-rolled steel sheet, and a galvanizing layer formed on the intermetallic compound, the cold-rolled steel sheet having a specific composition and a microstructure having a martensite area ratio of 7% or more and less than 25% and a ferrite area ratio of 50% or more and which includes a base metal surface portion in which the amount of internal oxides per single side is 0.05 g/m.sup.2 or less.

A manufacturing method for steel sheets for containers produces steel sheets with excellent film adhesion qualities. This steel sheet for containers has, on a steel sheet, a chemical conversion coating with a metal Zr content of 1-100 mg/m.sup.2, a P content of 0.1-50 mg/m.sup.2, and an F content of no more than 0.1 mg/m.sup.2, upon which is formed a phenolic resin layer with a C content of 0.1-50 mg/m.sup.2. Moreover, the manufacturing method for steel sheets for containers is a method for obtaining the steel sheet for containers wherein the chemical conversion coating is formed on the steel sheet by subjecting the steel sheet to immersion in or electrolytic treatment with a treatment solution containing Zr ions, phosphoric acid ions, and F ions; and subsequently, the steel sheet upon which the chemical conversion coating has been formed is immersed in, or undergoes topical application of, an aqueous solution containing phenolic resin, then dried.

A method and system solution heat treat, at an elevated first temperature, a coil of aluminum alloy sheet to form a heat-treated coil and while at least a portion of the heat-treated coil is being solution heat treated, uncoil a heat-treated portion of the aluminum alloy sheet from the heat-treated coil and continuously quenching the uncoiled heat-treated portion to form a quenched sheet.

The present invention has as its object the provision of a coated steel member and coated steel sheet excellent in hydrogen embrittlement resistance in a corrosive environment and methods for manufacturing the same. The coated steel member of the present invention is provided on its surface with an Al—Fe-based coating containing Cu and one or more of Mo, Ni, Mn, and Cr in a total by mass % of 0.12% or more by heating, cooling, and manufacturing a coated steel sheet having a layer containing Cu on its surface under predetermined conditions.

Disclosed is a high-strength steel sheet having a tensile strength (TS) of 780 MPa or more and excellent in ductility, fatigue properties, stretch flangeability, surface characteristics, and sheet passage ability that can be obtained by providing a predetermined chemical composition and a steel microstructure that contains, by area, 20-50% of ferrite, 5-25% of bainitic ferrite, 1-10% of martensite, and 5-15% of tempered martensite, and that contains, by volume, 10% or more of retained austenite, in which the retained austenite has a mean grain size of 2 μm or less, a mean Mn content in the retained austenite in mass % is at least 1.2 times the Mn content in the steel sheet in mass %, the retained austenite has a mean free path of 1.2 μm or less, and the tempered martensite has a mean free path of 1.2 μm or less.