Abstract: The present invention provides a galvannealed steel sheet excellent in the adhesion with a base steel sheet and a manufacturing method thereof. The galvannealed steel sheet according to the invention has, in an interface between a galvannealed layer and the base steel sheet thereon the galvannealed layer is formed, an irregularity that has a depth of 10 nm or more at a pitch of 0.5 ?m or less at least one per 5 ?m of a length of the interface.

Abstract: An alloyed hot-dip galvanized steel sheet is obtained by forming a hot-dip galvanized layer on the surface of the steel sheet and then alloying the steel sheet. The steel sheet exhibits a potential of −850 mV or less when it is immersed in a zinc sulfate-sodium chloride electrolyte. Alternatively, when it is electrolyzed according to constant potential electrolysis process in a zinc sulfate-sodium chloride electrolyte at a potential in a range from −940 mV to −920 mV, the quantity of electricity consumed is less than or equal to 0.5 C/cm2. The steel sheet exhibits excellent processability and particularly excellent sliding property.

Abstract: The present invention provides for a zinc-based coated steel sheet having a zinc-based coating layer and a lubricant film, which is formed on the zinc-based coating layer, containing zinc phosphate particles in an amount of 50 wt. % or more, and having substantially no reaction layer formed by reaction between the zinc-based coating and the zinc phosphate particles, and a method for the manufacture thereof. The zinc-based coated steel sheet according to the present invention has an excellent anti-peeling property, excellent frictional property, even in the non-lubricated condition which occurs at areas where the press oil film is broken, and excellent anti-galling property.

Abstract: A method for determining a quantity of each of alloy phases in the plating layer includes subjecting each alloy phase in the plating layer to constant potential electrolysis in each of a plurality of ranges of potentials obtained on the basis of the immersion potential of each alloy phase and the immersion potential of a basis metal, by using a plated metal material having different kinds of alloy phases in the plating layer as the anode, to determine the quantity of each alloy phase in the plating layer on the basis of the quantity of electricity consumed in each range of the potentials during the electrolysis.

Abstract: A method for determining a quantity of each of alloy phases in the plating layer includes subjecting each alloy phase in the plating layer to constant potential electrolysis in each of a plurality of ranges of potentials obtained on the basis of the immersion potential of each alloy phase and the immersion potential of a basis metal, by using a plated metal material having different kinds of alloy phases in the plating layer as the anode, to determine the quantity of each alloy phase in the plating layer on the basis of the quantity of electricity consumed in each range of the potentials during the electrolysis.

Abstract: An alloyed hot-dip galvanized steel sheet is obtained by forming a hot-dip galvanized layer on the surface of the steel sheet and then alloying the steel sheet. The steel sheet exhibits a potential of −850 mV or less when it is immersed in a zinc sulfate-sodium chloride electrolyte. Alternatively, when it is electrolyzed according to constant potential electrolysis process in a zinc sulfate-sodium chloride electrolyte at a potential in a range from −940 mV to −920 mV, the quantity of electricity consumed is less than or equal to 0.5 C/cm2. The steel sheet exhibits excellent processability and particularly excellent sliding property.

Abstract: The present invention provides a high strength thin excellent workability and galvanizability, having a composition comprising from 0.01 to 0.20 wt. % C, up to 1.0 wt. % Si, from 1.0 to 3.0 wt. % Mn, up to 0.10 wt. % P, up to 0.05 wt. % S, up to 0.10 wt. % Al, up to 0.010 wt. % N, up to 1.0 wt. % Cr, from 0.001 to 1.00 wt. % Mo, and the balance Fe and incidental impurities, wherein a band structure comprising a secondary phase has a thickness satisfying the relation Tb/T≦0.005 (where, Tb: average thickness of the band structure in the thickness direction of steel sheet; T: steel sheet thickness), and a manufacturing method thereof, and a manufacturing method of a high strength hot-dip galvanized steel sheet or a high strength galvannealed steel sheet applying hot-dip galvanizing or further galvannealing, and giving an excellent workability, a high tensile strength, and excellent galvanizability, coating adhesion and corrosion resistance.

Abstract: Galvannealed steel sheet and method, made by applying hot-dip galvanizing to a steel sheet, heating at a heating rate of at least about 10° C./second to a maximum sheet temperature within a range of from about 470 to 550° C., and applying an alloying treatment; the Al content XAl% in the hot-dip galvannealing layer and the coating weight W g/m2 satisfy the following equation (1); thereby producing a Zn—Fe galvannealing layer having an iron content of from about 7 to 12%; the galvannealed steel sheet has intensities of &zgr;-phase, &dgr;1-phase and &Ggr;-phase that satisfy the following equations (4) and (5) as observed through X-ray diffraction with the galvannealing layer peeled off the galvannealed steel sheet at the galvannealing/steel sheet interface, and the galvannealed steel sheet having excellent press workability, having a whiteness and a glossiness within prescribed ranges: 5≦W×(XAl−0.12)≦15  (1) I(&zgr;:1.26)/I(&dgr;1:2.13)≦0.

Abstract: A method of manufacturing a galvanized steel sheet with high press formability, the sheet having an inorganic compound on a metallic galvanized-layer thereof. The method includes the step of effecting a galvanization on a steel sheet followed by an alloying treatment. The sheet of galvanized steel is immersed in a bath of an aqueous solution containing 0.1 wt % or more of borate of an alkali metal, and then taking the steel sheet out of the bath and effecting such control as to make the amount of deposition of the water-containing borate film on the steel sheet surface to range from 10 to 1,000 mg/m.sup.2, and then heating the steel sheet at a temperature ranging from 60.degree. to 400.degree. C. Thereafter, the steel sheet is cooled to a normal temperature.

Abstract: In connection with a process of implementing galvanizing and galvannealing on steel strips containing highly oxidizable elements such as Si, Mn, P, Ti, Nb, Al, Ni, Cu, Mo, V, Cr, and B, after annealing in a continuous line or implementing electroplating after annealing, the present invention provides a method for restraining non-plating at low cost in a stable manner and a surface treated steel strip having minimal non-plating. By applying on at least one surface of a steel strip a Fe plating having a coating weight of 0.1-10 g/m.sup.2 and an oxygen content of 0.1-10 wt %, followed by annealing and then zinc or zinc alloy plating, there is obtained a surface treated steel strip having minimal plating defects which includes a Fe plating layer immediately below a zinc or zinc alloy plating layer and a steel alloying element concentrated stratum immediately below the Fe plating layer. The Fe plating may be formed using an electroplating bath which contains 0.1-10 g/l of Fe.sup.

Abstract: The invention provides an aluminum alloy sheet having improved formability, an elongation of at least 30%, a sliding frictional resistance of up to 0.13 and minimized surface pressure dependency of sliding frictional resistance, comprising an aluminum alloy substrate containing at least 4 wt % of Mg and a Fe rich plating layer on a surface thereof in a coating weight of 1 to 50 g/m.sup.2. Also provided is a bake hardenable, surface treated aluminum alloy sheet having improved formability, an elongation of at least 25%, a sliding frictional resistance of up to 0.13 and minimized surface pressure dependency of sliding frictional resistance, comprising a bake hardenable aluminum alloy substrate containing Mg and Si in an amount of at least 0.4 wt % calculated as Mg.sub.2 Si and a Fe rich plating layer on a surface thereof in coating weight of 1 to 50 g/m.sup.2. By forming a zincate layer as an undercoat below the Fe rich plating layer, the plating adhesion is further improved.