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.

A hot-dip galvanized steel sheet including: a hot-dip galvanizing layer on at least one side of a base steel sheet. The hot-dip galvanizing layer has a Fe content of more than 0% to 3.0% and an Al content of more than 0% to 1.0%. The hot-dip galvanized steel sheet includes a Fe—Al alloy layer provided on an interface between the hot-dip galvanizing layer and the base steel sheet and a fine-grain layer provided in the base steel sheet and directly in contact with the Fe—Al alloy layer. The Fe—Al alloy layer has a thickness of 0.1-2.0 μm. The fine-grain layer has an average thickness of 0.1-5.0 μm, includes a ferrite phase with an average grain diameter of 0.1-3.0 μm, and contains oxides of one or more out of Si and Mn, a maximum diameter of the oxides being 0.01-0.4 μm.

A Zn—Mg alloy plated steel material having excellent adhesion to plating and corrosion resistance comprises base steel and a plating layer formed on the surface of the base steel, wherein the plating layer comprises a Zn single phase, a Mg single phase, an MgZn.sub.2 alloy phase, and an Mg.sub.2Zn.sub.11 alloy phase, the Zn single phase is contained in the plating layer at a proportion of 15 to 19 volume %, and the proportion of the Zn single phase in a lower t/2 area of the plating layer adjacent to the base steel may be greater than the proportion of the Zn single phase in an upper t/2 area of the plating layer on the surface layer side of the plating layer. (Here, t means the thickness (μm) of the plating layer).

The present invention relates to an alloy-coated steel sheet comprising: a steel sheet, and Al—Mg—Si—Zn alloy layer positioned on the steel sheet, wherein the Al—Mg—Si—Zn alloy layer comprises a Mg—Zn alloy phase, and wherein the Mg—Zn alloy phase comprises MgZn.sub.2 and Mg.sub.2Zn.sub.11, and the Mg—Zn alloy phase further comprises at least one of MgZn, Mg.sub.21Zn.sub.25, Mg.sub.51Zn.sub.20 and Mg.sub.2Zn.sub.3.

A coated substrate has a substrate and a coating system having one or more ceramic layers. At least a first layer of one of the one or more ceramic layers is a columnar layer having as-deposited columns and intercolumn gaps. The intercolumn gaps have a mean width at least one of: at least 4.0 micrometers; and at least 1.5% of a thickness of said first layer.

A galvanized dual phase steel sheet with a martensite phase and a ferrite phase and a composition containing within the following ranges by weight: carbon from about 0.01% to about 0.18%; manganese from about 0.2% to about 3%; silicon≤about 1.2%; aluminum from about 0.01% to about 0.1%; one or both of chromium and nickel from about 0.1% to about 3.5%; calcium from about 0.0003% to about 0.01%; phosphorus≤about 0.1%; sulfur≤about 0.03%; nitrogen≤about 0.02%; molybdenum≤about 1%; one or more of niobium and titanium≤about 1%; and boron≤about 0.006% by weight; and with the balance of the composition being iron and incidental ingredients. The steel sheet may be both galvanized and galvannealed.

There is provided a high-strength hot-dipped steel sheet having excellent coating adhesion and a method for manufacturing the steel sheet. The steel sheet has a chemical composition, and a coating layer is disposed on the steel sheet. The chemical composition includes, by mass %, C: 0.02% or greater and 0.30% or less, Si: 0.01% or greater and 2.0% or less, Mn: 0.2% or greater and 3.0% or less, P: 0.08% or less, S: 0.02% or less, and Al: 0.001% or greater and 0.40% or less, with the balance being Fe and incidental impurities. The coating layer has a coating weight per side of 30 to 90 g/m.sup.2 and contains exfoliated base steel in an amount of 0.3 to 1.5 g/m.sup.2.

Provided is a steel sheet for a hot press formed member having excellent painting adhesion and post-painting corrosion resistance, and a method for manufacturing the same. A steel sheet for hot press forming according to one aspect of the present invention comprises a base steel sheet and a plated layer formed on a surface of the base steel sheet, wherein the ratio of an area occupied by pores to the entire area of a surface layer portion may be 10% or more in a cross section of the surface layer portion observed when the plated layer is cut in a thickness direction thereof.

A method for producing a cold rolled steel sheet having a tensile strength≥1470 MPa and a total elongation TE≥19%, the method comprising the steps of annealing at an annealing temperature AT≥Ac3 a non-treated steel sheet whose chemical composition contains in weight %: 0.34%≤C≤0.40%, 1.50%≤Mn≤2.30%, 1.50≤Si≤2.40%, 0%<Cr≤0.5%, 0%<Mo≤0.3%, 0.01%≤Al≤0.07%, the remainder being Fe and unavoidable impurities, quenching the annealed steel sheet by cooling it to a quenching temperature QT<Ms transformation point and between 150° C. and 250° C., and making a partitioning treatment by reheating the quenched steel sheet to a partitioning temperature PT between 350° C. and 420° C. and maintaining the steel sheet at this temperature during a partitioning time Pt between 15 seconds and 120 seconds.

A method for producing a cold rolled steel sheet having a tensile strength ≥1470 MPa and a total elongation TE≥19%, the method comprising the steps of annealing at an annealing temperature AT≥Ac3 a non-treated steel sheet whose chemical composition contains in weight %: 0.34%≤C≤0.40%, 1.50%≤Mn≤2.30%, 1.50≤Si≤2.40%, 0<Cr≤0.5%, 0<Mo≤0.3%, 0.01%≤Al≤0.07%, the remainder being Fe and unavoidable impurities, quenching the annealed steel sheet by cooling it to a quenching temperature QT<Ms transformation point and between 150° C. and 250° C., and making a partitioning treatment by reheating the quenched steel sheet to a partitioning temperature PT between 350° C. and 420° C. and maintaining the steel sheet at this temperature during a partitioning time Pt between 15 seconds and 120 seconds.