High strength galvannealed steel sheet having, a) a composition consisting of (in wt. %): C 0.10-0.2, Mn 2.0-3.0, Si 0.2-0.5, Cr 0.1-0.7, Ti 0.01-0.07, Al≤0.2, Nb<0.05, Mo<0.1, optionally B 0.001-0.005, balance Fe apart from impurities, b) a multiphase microstructure comprising (in vol. %) retained austenite 4-20, martensite 5-25, bainitic ferrite ≤10, polygonal ferrite ≤10, balance bainite+tempered martensite 50-90, c) a tensile strength (Rm) 1180-1300 MPa, a yield strength (R.sub.p0.2) 800-970 MPa, an elongation (A50) ≥8%, or an elongation (A80) ≥6%, and d) a bendability value Ri/t of ≤4 for a sample having the size of 35 mm×100 mm, wherein Ri is the bending radius in mm and t is the thickness in mm of the steel sheet.

The present invention relates to aluminum plated steel sheet which does not require coating after plating and is high in production flexibility enabling application of conventional production processes as they are or exhibits excellent corrosion resistance to flex fuels and further is excellent in appearance and to fuel tanks characterized by being produced using the steel sheet. The Si, Mg, Ca, and Ti ingredients in the aluminum plating layer are defined and the cooling method after hot dip aluminum coating is controlled to make Mg.sub.2Si particles with a long axis of 10 μm or less and an aspect ratio of 1 to 3 finely disperse in the plating layer. Due to the Mg.sub.2Si particles, it is possible to give an excellent corrosion resistance to flex fuels and suppress the deterioration in appearance due to MgO.

A method for producing a flat steel product with high reflectivity, in which at least one surface has an arithmetic mean roughness Ra of less than 0.03 μm includes providing a flat steel product, at least one surface of which has an arithmetic mean roughness Ra of less than 2.5 μm. The flat steel product is cold rolled in a plurality of rolling passes. Also a flat steel product with high reflectivity in the finished re-rolled state on at least one of its surface has a low arithmetic mean roughness, a high gloss, and a high directed reflection. A solar concentrator is produced from such a flat steel product.

Zn alloy plated steel material having excellent weldability and processed-part corrosion resistance and a method for production of Zn alloy plated steel material are provided. In the Zn alloy plated steel material comprising base steel material and a Zn alloy plating layer, the Zn alloy plating layer includes, by wt %, Al: 0.1-5.0%, Mg: 0.1-5.0%, as well as a remainder of Zn and inevitable impurities. The Zn alloy plated steel material includes a lower interface layer and an upper interface layer between the base steel material and the Zn alloy plating layer, wherein the lower interface layer is formed on the base steel material and has a dense structure, and the upper interface layer is formed on the lower interface layer and has a network-type or island-type structure.

A low-yield ratio high-strength electric resistance welded steel pipe has a yield ratio of 80% or less and a TS of 655 MPa or more. A steel material has a composition containing 0.38% to 0.45% C, 0.1% to 0.3% Si, 1.0% to 1.8% Mn, 0.03% or less P, 0.03% or less S, 0.01% to 0.07% sol. Al, and 0.01% or less N on a mass basis.

A flat steel product for hot forming may be produced from a steel substrate that includes a steel comprising 0.1-3% by weight Mn and up to 0.01% by weight B, along with a protective coating that is applied to the steel substrate. The protective coating may be based on Al and may contain up to 20% by weight of other alloy elements. Also disclosed are methods for producing such flat steel products, steel components, and methods for producing steel components. Absorption of hydrogen is minimized during heating necessary for hot forming. This is achieved at least in part through an alloy constituent of 0.1-0.5% by weight of at least one alkaline earth or transition metal in the protective coating, wherein an oxide of the alkaline earth or transition metal is formed on an outer surface of the protective coating during hot forming of the flat steel product.

Disclosed is an amorphous, ductile brazing foil with a composition consisting essentially of Ni.sub.restCr.sub.aB.sub.bP.sub.cSi.sub.d with 2 atomic percent≦a≦30 atomic percent; 0.5 atomic percent≦b≦14 atomic percent; 2 atomic percent≦c≦20 atomic percent; 0 atomic percent≦d≦14 atomic percent; incidental impurities≦0.5 atomic percent; rest Ni, where c>b>c/15 and 10 atomic percent≦b+c+d≦25 atomic percent. Also disclosed is amorphous, ductile Ni-based brazing foil having a composition consisting essentially of Ni.sub.restCr.sub.aB.sub.bP.sub.cSi.sub.dC.sub.eX.sub.fY.sub.g wherein a, b, c, d, e, f, and g are numbers such that 2 atomic percent≦a≦30 atomic percent; 0.5 atomic percent≦b≦14 atomic percent; 2 atomic percent≦c≦20 atomic percent; 0 atomic percent≦d≦14 atomic percent; 0 atomic percent≦e≦5 atomic percent; 0 atomic percent≦f≦5 atomic percent; 0 atomic percent≦g≦20 atomic percent; wherein incidental impurities are present, if at all, in amounts≦0.5 atomic percent; wherein rest indicates that the balance of the composition is Ni; wherein c>b>c/15; wherein 10 atomic percent≦b+c+d≦25 atomic percent, wherein X is one or more of the elements Mo, Nb, Ta, W and Cu; and wherein Y is one or both of the elements Fe and Co. Also disclosed are methods for making and using these brazing foils, and brazed objects produced therefrom.

Disclosed is a hot-dip Al—Zn alloy coated steel sheet having excellent anti-corrosion property after coating, and a method for producing the same. In the disclosure, the hot-dip Al—Zn alloy coated steel sheet has a hot-dip coating layer containing by mass %, Al: 25% to 90%, and at least one of Sn: 0.01% to 2.0%, In: 0.01% to 10%, and Bi: 0.01% to 2.0%.

Provided is an alloy-plated steel material that can be used in home appliances, automobiles, and construction materials and the like and, more particularly, to an alloy-plated steel material having excellent corrosion resistance and high surface quality.

Provided is a multilayer zinc alloy plated steel material comprising a base steel material and multiple plating layers formed on the base steel material, wherein each of the multiple plating layers includes one of a Zn plating layer, a Mg plating layer, and a Zn—Mg alloy plating layer, and the ratio of the weight of Mg contained in the multiple plating layers to the total weight of the multiple plating layers is from 0.13 to 0.24.