Abstract: High strength steel sheet and plated steel sheet having high plateability, LME resistance, and hydrogen embrittlement resistance, that is, steel sheet containing C: 0.05 to 0.40%, Si: 0.2 to 3.0%, Mn: 0.1 to 5.0%, and sol. Al: 0.4 to 1.50%, having an internal oxidation layer including fine granular oxides in a surface layer of the steel sheet, a number density of fine granular oxides in the internal oxidation layer being 4.0/?m2 or more, and including a surface depleted layer with a steel composition not including oxides which satisfies, by mass %, Si?0.6% and Al?0.05% at a depth of ½ of the average depth of the internal oxidation layer calculated from the cross-sectional SEM image of the steel sheet, and a plated steel sheet using the same.

Abstract: A hot stamped body 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, the plating layer comprises an interfacial layer positioned at an interface with the steel base material and containing Fe and Al and a main layer positioned on the interfacial layer, the main layer comprises, by area ratio, 10.0 to 70.0% of an Mg—Zn containing phase and 30.0 to 90.0% of an Fe—Al containing phase, the Mg—Zn containing phase comprises at least one selected from the group consisting of an MgZn phase, Mg2Zn3 phase, and MgZn2 phase, and the Fe—Al containing phase comprises an FeAl phase and Fe—Al—Zn phase and an area ratio of the Fe—Al—Zn phase in the main layer is more than 10.0 to 75.0%.

Abstract: A steel welded member comprising a plurality of Zn-based plated steel materials, each having a Zn-based plating layer on a surface of a steel material, joined together through at least one spot weld, wherein the steel material contains, by mass %, C: 0.05 to 0.40%, Si: 0.2 to 3.0%, and Mn: 0.1 to 5.0%, the steel welded member includes, by area ratio, 20 to 80% of a ? phase (Fe3 Zn10) and at least one oxide with a long axis of 0.5 ?m or more in a region up to 0.5 mm from an end part of a pressure weld of the spot weld.

Abstract: A galvanized steel sheet comprising a steel sheet containing C: 0.05 to 0.30%, Si: 0.01 to 3.00%, Mn: 0.80 to 3.00%, and Al: 0.010 to 2.000% and having a thickness of 0.10 to 0.95 mm, and a galvanized layer on the steel sheet, wherein a tensile strength is 550 to 1500 MPa, and, when defining a thickness of an internal oxide layer per surface of the steel sheet as “A” (?m), a thickness of a decarburized layer per surface of the steel sheet as “B” (?m), and a thickness of the steel sheet as “t” (?m), A/B: 0.01 to 0.50 and B/t: 0.001 to 0.200.

Abstract: To improve both the slow temperature increasing rate of an overlapped part and the difference in temperature increasing rate between an overlapped part and a one-sheet part when an Al-based plated steel sheet is used as a raw material. An overlapped blank for hot stamping according to the present invention includes: a first Al-based plated steel sheet having a sheet thickness t1; and a second Al-based plated steel sheet having a sheet thickness t2, the second Al-based plated steel sheet overlapped and welded on the first steel sheet, having a smaller area than the first steel sheet, and including a carbon-based black coating as an upper layer of an Al-based plated layer on the side not in contact with the first Al-based plated steel sheet, in which the overlapped blank for hot stamping satisfies (1) Expression to (5) Expression.

Abstract: High strength plated steel sheet having high hydrogen embrittlement resistance, that is, alloyed hot dip galvannealed steel sheet including steel sheet containing C: 0.05 to 0.40%, Si: 0.2 to 3.0%, Mn: 0.1 to 5.0%, and sol. Al: 0.4 to 1.50% and a alloyed hot dip galvannealed layer deposited on at least one surface of the steel sheet to 10 to 100 g/m2 and containing Fe: 5.0 to 15.0% and Al: 0.01 to 1.0%, having an internal oxidation layer including grain boundary oxides in a surface layer of the steel sheet, when examining a cross-section of a surface layer of the steel sheet, a Ratio A of the length of the grain boundary oxides projected an interface of the steel sheet and the alloyed hot dip galvannealed layer to the length of interface is 50% or more and 100% or less, and a surface depleted layer with a steel composition not including the grain boundary oxides which satisfies, by mass %, Si?0.6% and Al?0.05% is included at a depth of ½ of the average depth of the internal oxidation layer.

Abstract: Provided is a hot stamped body comprising a steel base material, an Al-plating layer formed on at least one surface of the steel base material, a coating formed on the Al-plating layer and containing ZnO particles and CeO2 particles having an average particle size smaller than an average particle size of the ZnO particles, and a Zn- and Al-containing complex oxide layer formed between the Al-plating layer and the coating. Further, provided is a method for producing a hot stamped body comprising forming an Al-plating layer on at least one side of a steel sheet, coating a surface of the Al-plating layer with an aqueous solution containing ZnO particles and CeO2 particles, then heating it to form a coating containing ZnO particles and CeO2 particles on the Al-plating layer, and hot pressing the steel sheet.

Abstract: A non-oriented electrical steel sheet according to one embodiment of the present invention includes a base metal steel sheet, and a composite coating film composed of a Zn-containing phosphate and an organic resin, the composite coating film being formed on a surface of the base metal steel sheet, wherein: a content of Zn in the composite coating film is 10 mg/m2 or more per side; and the product of an amount of oxygen in the base metal steel sheet and a sheet thickness of the base metal steel sheet is 50 ppm·mm or less.

Abstract: A manufacturing method includes: heating an overlapped blank; transferring the heated overlapped blank; and a step of performing presswork on the heated overlapped blank by using a die. In the heating step, when sheet-thicknesses of the first and second steel sheets are set, respectively, and an average heating rate at a sheet temperature from 20 to 800° C. of a portion with a total sheet thickness of an overlapped portion, and a non-overlapped portion are set, the total sheet thickness is 2.5 to 5.0 mm, a maximum length of the overlapped portion is 100 to 1100 mm, an area of the first steel sheet, an area of a portion, of the second steel sheet, overlapped with the first steel sheet, and the average heating rates satisfy Expressions (1) to (3), and heating is performed at a temperature and for a time within a specific range on a plane of coordinates.

Abstract: An Al plated electric resistance welded steel pipe for hardening use suppressing the formation of scale to the inside of the plating layer while performing hot forming and an Al plated hollow member using that Al plated electric resistance welded steel pipe, wherein the Al plated electric resistance welded steel pipe for hardening use is comprised of a base material made of a tubular steel plate and having a predetermined chemical composition and an electric resistance welded zone provided at a seam portion of the steel plate and extending in a longitudinal direction of the steel plate, the base material is further provided with an intermetallic compound layer positioned on the surface of the steel plate and including an Al—Fe—Si-based intermetallic compound and an Al plating layer positioned on the surface of the intermetallic compound layer and containing Al and Si, and 70×X/D?Y/t?30 is satisfied, wherein X (?m) is a thickness of the intermetallic compound layer, Y (?m) is a thickness of the Al plating laye

Abstract: A non-oriented electrical steel sheet according to one embodiment of this invention includes a base metal steel sheet and a composite coating film composed of a Zn-containing phosphate and an organic resin, the composite coating film being formed on a surface of the base metal steel sheet. A molar ratio of Zn to all metal components in the composite coating film is 10 mol % or more, and after the non-oriented electrical steel sheet is boiled for 20 minutes in boiled distilled water, an amount of soluble Zn in the distilled water is 1.0 mg/m2 or more. The method for determining the amount of soluble Zn is in accordance with JIS K 0102: 2016 “Testing Methods for Industrial Wastewater”, 53.3 “ICP Emission Spectroscopy”.

Abstract: High strength steel sheet and plated steel sheet having high plateability, LME resistance, and hydrogen embrittlement resistance, that is, steel sheet containing C: 0.05 to 0.40%, Si: 0.2 to 3.0%, Mn: 0.1 to 5.0%, and sol. Al: 0.4 to 1.50%, having an internal oxidation layer including fine granular oxides, coarse granular oxides, and grain boundary oxides in a surface layer of the steel sheet, a number density of fine granular oxides in the internal oxidation layer being 4.0/?m2 or more, a number density of coarse granular oxides in the internal oxidation layer being 4.0/25 ?m2 or more, having a Ratio A of the length of the grain boundary oxides projected on the surface of the steel sheet to the length of the surface of the steel sheet when examining a cross-section of the surface layer of the steel sheet being 50% or more and 100% or less, and including a surface depleted layer with a steel composition not including oxides which satisfies, by mass %, Si?0.6% and Al?0.

Abstract: A plated steel sheet for hot stamping according to one aspect of the present invention includes a steel sheet, a plating layer formed on either surface or both surfaces of the steel sheet and having an Al content of 60 mass % or more, and a surface film layer formed on the plating layer. A thickness t of the plating layer is 10 to 60 ?m. An average crystal grain diameter of the plating layer in a thickness range from an interface between the plating layer and the surface film layer to a position at ? of the thickness t is 2t/3 or less and 15.0 ?m or less. A surface film layer contains particles containing one or more elements selected from A group elements consisting of Sc, V, Mn, Fe, Co, Ce, Nb, Mo, and W. A total content of the A group elements is 0.01 to 10.0 g/m2. An average grain diameter of the particles containing the A group elements is 0.05 to 3.0 ?m.

Abstract: The present invention relates to a galvanized steel sheet comprising steel sheet containing C: 0.05 to 0.30%, Si: 0.01 to 3.00%, Mn: 0.80 to 3.00%, and Al: 0.010 to 2.000% and having a thickness of 0.10 to 0.95 mm, and a galvanized layer on the steel sheet, wherein a tensile strength is 550 to 1500 MPa, and, when defining a thickness of an internal oxide layer per surface of the steel sheet as “A” (?m), a thickness of a decarburized layer per surface of the steel sheet as “B” (?m), and a thickness of the steel sheet as “t” (?m), A/B: 0.01 to 0.50 and B/t: 0.001 to 0.200.

Abstract: A steel sheet comprising, by mass %, C: 0.05 to 0.40%, Si: 0.2 to 3.0%, and Mn: 0.1 to 5.0%, wherein a surface layer of the steel sheet contains granular oxides, an average grain size of the granular oxides is 300 nm or less, a number density of granular oxides is 4.0/?m2 or more, the steel sheet comprises an Si—Mn depleted layer having a thickness of 3.0 ?m or more from the surface of the steel sheet, and Si and Mn contents of the Si—Mn depleted layer not containing oxides at the ½ position of the thickness are respectively less than 10% of the Si and Mn contents at the sheet thickness center part of the steel sheet, and a plated steel sheet using the same are provided.

Abstract: A steel welded member comprising a plurality of Zn-based plated steel materials, each having a Zn-based plating layer on a surface of a steel material, joined together through at least one spot weld, wherein the steel material contains, by mass %, C: 0.05 to 0.40%, Si: 0.2 to 3.0%, and Mn: 0.1 to 5.0%, the steel welded member includes, by area ratio, 20 to 80% of a ? phase (Fe3 Zn1 0) and at least one oxide with a long axis of 0.5 ?m or more in a region up to 0.5 mm from an end part of a pressure weld of the spot weld.

Abstract: A steel sheet comprising, by mass %, C: 0.05 to 0.40%, Si: 0.2 to 3.0%, and Mn: 0.1 to 5.0%, wherein a surface layer of the steel sheet contains grain boundary oxides, a Ratio A of a length of the grain boundary oxides projected on a surface of the steel sheet to a length of the surface of the steel sheet is 50% or more and 100% or less, a number density of granular oxides is less than 4.0/?m2, the steel sheet comprises an Si—Mn depleted layer having a thickness of 3.0 ?m or more from the surface of the steel sheet, and Si and Mn contents of the Si—Mn depleted layer at the ½ position of the thickness and not containing oxides are respectively less than 10% of the Si and Mn contents at a sheet thickness center part of the steel sheet, and a plated steel sheet using the same are provided.

Abstract: A hot stamped body 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, the plating layer comprises an interfacial layer positioned at an interface with the steel base material and containing Fe and Al and a main layer positioned on the interfacial layer, the main layer comprises, by area ratio, 10.0 to 90.0% of an Mg—Zn containing phase, 5.0 to less than 30.0% of an Fe—Al containing phase, and 2.0 to 25.0% of an Al—Si containing oxide phase, the Mg—Zn containing phase comprises at least one selected from the group consisting of an MgZn phase, Mg2Zn3 phase, and MgZn2 phase, and the Fe—Al containing phase comprises at least one of an FeAl phase and Fe—Al—Zn phase.

Abstract: High strength plated steel sheet having high hydrogen embrittlement resistance, that is, alloyed hot dip galvannealed steel sheet including steel sheet containing C: 0.05 to 0.40%, Si: 0.2 to 3.0%, Mn: 0.1 to 5.0%, and sol. Al: 0.4 to 1.50% and a alloyed hot dip galvannealed layer deposited on at least one surface of the steel sheet to 10 to 100 g/m2 and containing Fe: 5.0 to 15.0% and Al: 0.01 to 1.0%, having an internal oxidation layer including grain boundary oxides in a surface layer of the steel sheet, when examining a cross-section of a surface layer of the steel sheet, a Ratio A of the length of the grain boundary oxides projected an interface of the steel sheet and the alloyed hot dip galvannealed layer to the length of interface is 50% or more and 100% or less, and a surface depleted layer with a steel composition not including the grain boundary oxides which satisfies, by mass %, Si?0.6% and Al?0.05% is included at a depth of ½ of the average depth of the internal oxidation layer.

Abstract: High strength steel sheet and plated steel sheet having high plateability, LME resistance, and hydrogen embrittlement resistance, that is, steel sheet containing C: 0.05 to 0.40%, Si: 0.2 to 3.0%, Mn: 0.1 to 5.0%, and sol. Al: 0.4 to 1.50%, having an internal oxidation layer including fine granular oxides in a surface layer of the steel sheet, a number density of fine granular oxides in the internal oxidation layer being 4.0/?m2 or more, and including a surface depleted layer with a steel composition not including oxides which satisfies, by mass %, Si?0.6% and Al?0.05% at a depth of ½ of the average depth of the internal oxidation layer calculated from the cross-sectional SEM image of the steel sheet, and a plated steel sheet using the same.