Provided is a plated steel sheet having an excellent quality with fine and even plating texture, the plated steel sheet including a base steel sheet and a Zn plating layer formed on the base steel sheet, wherein a Zn crystal in the plating layer has a size of 5 μm or less.

Provided is a high-strength hot-rolled coated steel sheet having a TS of 980 MPa or more, excellent bulging formability and stretch flange formability, and excellent coatability. The high-strength hot-rolled coated steel sheet includes a steel sheet having a chemical composition containing, by mass %, C: 0.03% to 0.09%, Si: 0.01% to 1.60%, Mn: 2.20% to 3.60%, P: 0.100% or less, S: 0.0100% or less, Ti: 0.05% to 0.18%, B: 0.0005% to 0.0050%, Al: 0.005% to 0.40%, N: 0.010% or less, and a balance of Fe and inevitable impurities, in which a CSM value expressed by the equation 33.8[% C][% Mn]+12.4[% Si]/[% Mn] is 3.3 to 12.0, and a steel microstructure containing bainite in an amount of 85% or more in terms of area fraction and martensite in an amount of 2.0% or more and 15.0% or less in terms of area fraction and includes a coating layer or an alloyed coating layer on a surface of the steel sheet.

A coated steel product including a base steel, and a coating layer containing a Zn—Al—Mg alloy layer disposed on a surface of the base steel, in which the coating layer has a predetermined chemical composition, the coated steel product including dendrite-shaped MgZn.sub.2 phase having a surface roughness Sa of 50 nm or less on a surface of the Zn—Al—Mg alloy layer, an area ratio of the dendrite-shaped MgZn.sub.2 phase having a surface roughness Sa of 50 nm or less being from 30% to 80% within a region of an observable field of view of 5 mm.sup.2, and among the dendrite-shaped MgZn.sub.2 phase having a surface roughness Sa of 50 nm or less, a number of dendrite-shaped MgZn.sub.2 phase having an area of 0.1 mm.sup.2 or more being from 5 to 100 within a region of an observable field of view of 25 mm.sup.2.

A coated steel material including: a base steel, and a coating layer containing a Zn—Al—Mg alloy layer disposed on a surface of the base steel, wherein the coating layer has a predetermined chemical composition, and, in a backscattered electron image of the Zn—Al—Mg alloy layer that is obtained at a time of observing the surface of the Zn—Al—Mg alloy layer after polishing to ½ of the layer thickness, under a scanning electron microscope at a magnification of 100×, Al crystals are present, and the average value of the cumulative circumferential length of the Al crystals is 88 to 195 mm/mm.sup.2.

Provided is a low-density clad steel sheet having excellent formability and fatigue properties, including a base material; and cladding materials provided on both side surfaces of the base material, wherein the base material is a lightweight steel sheet including, by weight, C: 0.3 to 1.0%, Mn: 4.0 to 16.0%, Al: 4.5 to 9.0%, and a remainder of Fe and inevitable impurities, and each of the cladding materials is martensitic carbon steel including, by weight, C: 0.1 to 0.45%, Mn: 1.0 to 3.0%, and a remainder of Fe and inevitable impurities.

The present invention relates to an automotive steel sheet and, more specifically, provides: an ultrahigh-strength and high-ductility steel sheet ensuring ultrahigh strength and high ductility and, simultaneously, having excellent cold formability due to a high yield strength ratio, and improved collision characteristics.

A surface-treated steel sheet for a battery container includes a steel sheet, an iron-nickel diffusion layer formed on the steel sheet, and a nickel layer formed on the iron-nickel diffusion layer and constituting the outermost layer. When the Fe intensity and the Ni intensity are continuously measured from the surface of the surface-treated steel sheet for a battery container along the depth direction with a high frequency glow discharge optical emission spectrometric analyzer, the thickness of the iron-nickel diffusion layer being the difference (D2−D1) between the depth (D1) at which the Fe intensity exhibits a first predetermined value and the depth (D2) at which the Ni intensity exhibits a second predetermined value is 0.04 to 0.31 μm; and the total amount of the nickel contained in the iron-nickel diffusion layer and the nickel contained in the nickel layer is 10.8 to 26.7 g/m2.

A plated steel material comprising a steel base material and an Al—Zn—Mg-based plating layer formed on a surface of the steel base material, wherein the plating layer has a predetermined chemical composition, and in a surface structure of the plating layer, there is, by area ratio, 2.0% or more of an acicular Al—Zn—Si—Ca phase.

Provided is a steel sheet for a hot press formed member having excellent resistance to hydrogen delayed fracture, and a method for manufacturing the same. A steel sheet for a hot press formed member comprises: a base steel sheet; an aluminum alloy plating layer on a surface of the base steel sheet; and an oxide layer which is formed on a surface of the plating layer and has a thickness of 0.05 μm or more.

The present invention relates to a steel sheet for a hot press formed member having excellent coating adhesion, and a method for manufacturing the same. A steel sheet for hot press forming according to one aspect of the present invention is an aluminum alloy plated steel sheet, wherein an average Fe content in a plating layer may be 40 wt % or more, and a concentration gradient of a section having a Fe content of 45 wt % to 80 wt % in the plating layer may 7 wt %/μm or less of a concentration gradient at a section having an Fe content of 45% to 80% in the plating layer in a thickness direction from a surface of the plating layer according to a result of GDS analysis.