The present invention relates to a hot-rolled steel sheet for a high strength galvanized steel sheet, having excellent surface quality, and a method for producing the same, the hot-rolled steel sheet comprising, by weight %: C: 0.05 to 0.15%, Si: 0.03 to 0.10%, Mn: 0.7 to 1.39%, P: 0.001 to 0.05%, S: 0.001 to 0.03%, Al: 0.002 to 0.035%, and the remainder being Fe and unavoidable impurities. The weight ratio of Mn/Si is 15 to 25, the weight ratio of C/Si is 1 to 5, and the weight ratio of Si/P is 3 to 10. The hot-rolled steel sheet has a microstructure consisting of, in area fraction, 10 to 40% of bainite, 20 to 30% of pearlite and 40 to 60% of ferrite, and includes a ternary eutectic compound of FeO, Fe.sub.2SiO.sub.4 and Fe.sub.3(PO).sub.4 formed within 50 μm from the surface.

A canted coil spring includes a core wire 10 formed of steel having a pearlite structure; and a copper plating layer 20 formed of copper or a copper alloy and covering an outer circumferential surface 11 of the core wire 10. The steel contains 0.5 mass % or more and 1.0 mass % or less carbon, 0.1 mass % or more and 2.5 mass % or less silicon, and 0.3 mass % or more and 0.9 mass % or less manganese, with the balance being iron and inevitable impurities. The copper plating layer 20 has a crystallite size of 220±50 Å.

The present invention provides a carrier-attached copper foil, wherein an ultrathin copper foil is not peeled from the carrier prior to the lamination to an insulating substrate, but can be peeled from the carrier after the lamination to the insulating substrate. A carrier-attached copper foil comprising a copper foil carrier, an intermediate layer laminated on the copper foil carrier, and an ultrathin copper layer laminated on the intermediate layer, wherein the intermediate foil is configured with a Ni layer in contact with an interface of the copper foil carrier and a Cr layer in contact with an interface of the ultrathin copper layer, said Ni layer containing 1,000-40,000 μg/dm.sup.2 of Ni and said Cr layer containing 10-100 μg/dm.sup.2 of Cr is provided.

The hot-rolled coated steel sheet comprising: in wt %, C: 0.05-0.14%, Si: 0.1-1.0%, Mn: 1.0-2.0%, P: 0.001-0.05%, S: 0.001-0.01%, AI: 0.01-0.1%, Cr: 0.005-1.0%, Ti: 0.005-0.13%, Nb: 0.005-0.03%, N: 0.001-0.01%, Fe residues, and other inevitable impurities; a mixed structure of ferrite and bainite as a main phase; and as a remaining structure, one or more selected from the group consisting of martensite, austenite, and phase martensite (MA), wherein a fraction of the ferrite and bainite is 95-99 area % and Equation 1 is satisfied. [Equation 1] FCO.sub.{110}<112>+FCO.sub.{112}<111>≥10 where, FCO.sub.{110}<112> and FCO.sub.{112}<111>, each representing an area fraction occupied by a structure having ac crystal orientation of {110}<112> and {112}<111>.

The present disclosure provides a hot-press formed part comprising a plated steel sheet and an aluminum alloy plated layer formed on the plated steel sheet, wherein the aluminum alloy plated layer comprises: an alloying layer (I) formed on the plated steel sheet and containing, by weight %, 5-30% of Al; an alloying layer (II) formed on the alloying layer (I) and containing, by weight %, 30 to 60% of Al; an alloying layer (III) formed on the alloying layer (II) and containing, by weight %, 20-50% of Al and 5-20% of Si; and an alloying layer (IV) formed continuously or discontinuously on at least a part of the surface of the alloying layer (III), and containing 30-60% of Al, wherein the rate of the alloying layer (III) exposed on the outermost surface of the aluminum alloy plated layer is 10% or more.

This manufacturing method of a hot press-formed article includes a heating step of heating an Al-plated steel sheet and a forming step of obtaining a hot press-formed article using a die after the heating step, the Al-plated steel sheet has a base steel sheet, an Al plating layer, and a coating layer, the coating layer is a metal layer containing at least one metal of Mg, Ca, V, Ti, and Zn, a metal oxide layer containing an oxide of one or more of Mg, Ca, V, Ti, and Zn, or a mixed layer including the metal layer and the metal oxide layer, the die has a hard layer on a surface, HV.sub.Die that is a surface hardness of the die at a position of the hard layer is HV1500 or more and HV3800 or less, and a temperature Tm of the Al-plated steel sheet at a start of forming and an average movement velocity V of the die in the forming step satisfy 800−(HV.sub.Die/40)≤Tm≤850−(V/4)−(HV.sub.Die/100).

The present invention provides an iron-aluminum-based plated steel sheet, and a manufacturing method therefor, the iron-aluminum-based plated steel sheet comprising a base steel sheet and a plated layer formed on the surface of the base steel sheet, wherein the alloy plated layer comprises: a diffusion layer comprising an Fe—Al-based intermetallic compound having a cubic structure; and an alloyed layer formed on the diffusion layer and composed of an alloy phase differing from that of the cubic structure, the thickness of the diffusion layer is 3-20 μm, and the thickness of the diffusion layer is greater than 50% of the total thickness of the plated layer.

A welded steel part with a very high mechanical strength is provided. The welded steel part is obtained by heating followed by hot forming, then cooling of at least one welded blank obtained by butt welding of at least one first and one second sheet. The at least one first and second sheets including, at least in part, a steel substrate and a pre-coating which includes an intermetallic alloy layer in contact with the steel substrate, topped by a metal alloy layer of aluminum or aluminum-based alloy. A method for the fabrication of a welded steel part and the fabrication of structural or safety parts for automotive vehicles are also provided.

A hot-dip galvanized steel sheet wherein the hot-dip galvanized steel sheet comprises a base steel sheet and a hot-dip galvanized layer, a ferrite phase is, by volume fraction, 50% or less in a range of ⅛ thickness to ⅜ thickness centered at a position of ¼ thickness from the surface of the base steel sheet, a hard structure is 50% or more, wherein the hot-dip galvanized steel sheet has the hot-dip galvanized layer in which Fe is 5.0% or less and Al is 1.0% or less, and columnar grains formed of a ζ phase is 20% or more in an entire interface between the plated layer and the base steel sheet, on the surface of the base steel sheet in which a volume fraction of a residual austenite is 3% or less and a ratio of a volume fraction of the hard structure is 0.10 times or more to 0.90 times or less of that of the hard structure in the range of ⅛ thickness to ⅜ thickness in a range of 20 μm depth in a steel sheet direction originating an interface between the hot-dip galvanized layer and the base steel sheet, and wherein the hot-dip galvanized steel sheet has a refined layer at the side of the interface in the base steel sheet, and wherein an average thickness of the refined layer, an average grain size of ferrite in the refined layer and a maximum size of the oxide included in the refined layer are defined respectively.

A plated material includes a base metal made from Cu or an alloy containing Cu as a main raw material, an underlayer made from Ni formed on the base metal, and an Ag plated layer formed on the underlayer. A thickness of the underlayer is 0.1 μm to 1.0 μm. A thickness of the Ag plated layer is 1.0 μm or less.