Nippon Steel Corporation

Takuya Mitsunobu

Hiroshi Takebayashi

Kohei Tokuda

Takehiro Takahashi

Jun Maki

Mamoru Saito

Masaaki Uranaka

Yasuto Goto

Keitaro Matsuda

Atsushi Morishita

Kenichiro Matsumura

Toyomitsu Nakamura

Akihiro Sengoku

Masahiro Matsuba

Fumiaki Nakamura

Koji Kawanishi

Tetsuya Toba

Shinichi Yamaguchi

Hidetoshi Shindo

Yasuaki Kawamura

Nobuyuki Shimoda

Yoshinari Ishida

Yuto Fukuda

Ryohei Mimura

Makoto Akahoshi

Yusuke Kohigashi

Shota Hayashida

This plated steel material includes a steel sheet, a plated layer formed on the steel sheet, and an oxide layer formed on the plated layer, in which the plated layer has a chemical composition containing, by mass %, 1.0 to 60.0% of Al, 1.0 to 15.0% of Mg, 0 to 2.0% of Si, 0 to 2.0% of Ca, and 0 to 2.0% of Fe, and a remainder being of Zn and impurities, the oxide layer has a thickness of 5 nm or more, and a (Al+Mg)/Zn intensity ratio that is the ratio of the total of the maximum intensity of Al and the maximum intensity of Mg to the maximum intensity of Zn in energy dispersive X-ray analysis of the oxide layer is 1.0 or more, and the oxide layer includes an amorphous microstructure.

Plated steel material and photovoltaic power generation stand

To further improve electrodeposition coating properties in a weld bead zone. A welded joint according to the present invention includes: a first steel sheet and a second steel sheet; and a weld bead zone formed by arc welding or laser welding, wherein at least one of the first steel sheet or the second steel sheet has a plating layer composed of a predetermined component and an oxide layer located on the plating layer in a non-heat-affected zone, and the weld bead zone has a weld metal and a slag layer formed on part of a surface of the weld metal, and the slag layer contains, by mass % when oxygen is excluded, Al: 1.0 to 45.0% and Mg: 1.0 to 30.0%, with the balance composed of Fe, easily oxidizable metallic elements, and impurities.

Welded joint

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 Γ phase (FeZn) and at least one oxide with a long axis of 0.5 μm or more in a region up to 0.5 mm from an end part of a pressure weld of the spot weld.

Steel welded member

This plated steel sheet includes a base steel sheet, a plated layer formed on a surface of the base steel sheet, and an oxide film formed on a surface of the plated layer, the plated layer has a chemical composition containing Sc: 0.000010 to 4.0% in mass %, and has a cross section, in the thickness direction, in which the area fraction of an intermetallic compound phase containing Sc and having an equivalent circle diameter of 5.0 μm or less is 0.1 to 10.0%, and the oxide film has a thickness of 10 nm or more.

Plated steel sheet

This plated steel sheet includes a steel sheet, and a plated layer disposed on a surface of the steel sheet, in which the plated layer has a chemical composition containing, in mass %, Al: 10.0 to 25.0%, Mg: 3.0 to 10.0%, Fe: 0.01 to 2.0%, and Si: more than 0 to 2.0%, with a remainder including Zn and impurities, and a number density of MgSi phases having a major axis of 2 μm or more exposed on the surface of the plated layer is 3 to 150 per area of 10,000 μm.

To more reliably suppress LME and blowhole formation while maintaining excellent corrosion resistance. A plated steel sheet according to the present invention, includes: a steel sheet as a base material; a plating layer located on at least part of a surface of the steel sheet; and an oxide layer located on a surface of the plating layer, where a chemical composition of the plating layer is made up of prescribed components, and Zn and impurities as the balance, and when a position at a depth of 5 nm from an uppermost surface of the oxide layer is observed by X-ray photoelectron spectroscopy (XPS), a value of an intensity ratio ([Al—O]+[Mg—O])/[Zn—O]) calculated from intensity of peaks respectively attributed to an Al—O bond, an Mg—O bond, and a Zn—O bond is 5.0 or more.

This hot stamped member includes: a steel; and a plating layer formed on the steel, in which the plating layer has a predetermined chemical composition, the plating layer contains a Zn-based oxide including one or two of a Zn oxide and a Zn—Mg oxide having a size of 1.0 μm or more and 10.0 μm or less in a thickness direction of the plating layer and 0.1 μm or more in a direction perpendicular to the thickness direction, and in a cross section of the plating layer in the thickness direction, when a length of an interface between the plating layer and the steel is indicated as Le, a sum of lengths of the Zn-based oxide projected onto the interface from an upper surface of the plating layer is indicated as ΣLi, and a sum of lengths of portions of the Zn-based oxide in contact with the plating layer projected onto the interface from the upper surface of the plating layer is indicated as ΣLai, ΣLi/Le≥0.10 and ΣLai/ΣLi≥0.50 are satisfied.

Hot stamped member

A hot stamped steel includes a base material that is formed of steel, a plated layer that is formed on a surface of the base material, and a phosphate coating that is formed on a surface of the plated layer; chemical composition of the plated layer contains 20.00 to 45.00 mass % of Al, 10.00 to 45.00 mass % of Fe, 4.50 to 15.00 mass % of Mg, 0.10 to 3.00 mass % of Si, 0.05 to 3.00 mass % of Ca, and the plated layer may further contain one or more of Sb, Pb, Cu, Sn, Ti, Sr, Cr, Ni, and Mn with a remainder of Zn and impurities; the phosphate coating comprises zinc phosphate crystals containing 5.0 to 50.0 mass % of Mg and 0.5 to 5.0 mass % of Ca; and the adhesion amount of the phosphate coating per one surface is in a range of 0.1 to 10.0 g/m.

Hot stamped steel

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/mand 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.

Alloyed hot dip galvannealed steel sheet

This plated steel includes: a steel; and a plating layer formed on the steel, in which the plating layer contains, as a chemical composition, by mass %, Zn: 1.0% to 30.0%, Mg: 0% to 10.0%, Si: 0.05% to 10.0%, Fe: 0 to 10.0%, 0% to 5.00% in total of one or two or more selected from Ca: 0% to 3.00%, Sb: 0% to 0.50%, Pb: 0% to 0.50%, Sr: 0% to 0.50%, Sn: 0% to 1.00%, Cu: 0% to 1.00%, Ti: 0% to 1.00%, Ni: 0% to 1.00%, Mn: 0% to 1.00%, Cr: 0% to 1.00%, La: 0% to 1.00%, Ce: 0% to 1.00%, Zr: 0% to 1.00%, and Hf: 0% to 1.00%, and a remainder of Al and impurities, a microstructure of the plating layer contains an α phase which is a solid solution of Al and Zn, and the α phase contains a Zn phase having a grain size of 10 to 200 nm in a number density of 10/100 μmor more.

Plated steel

This hot-dip Zn-based plated steel sheet includes a steel sheet and a plating layer formed on at least part of a surface of the steel sheet, in which the plating layer has a chemical composition that includes, by mass %, Al: 6.00% to 35.00%, Mg: 2.00% to 12.00%, Ca: 0.005% to 2.00%, Si: 0% to 2.00%, Fe: 0% to 2.00%, Sb: 0% to 0.50%, Sr: 0% to 0.50%, Pb: 0% to 0.50%, Sn; 0% to 1.00%, Cu: 0% to 1.00%, Ti: 0% to 1.00%, Ni: 0% to 1.00%, Mn: 0% to 1.00%, Cr: 0% to 1.00%, and a remainder: Zn and impurities; the plating layer has an area ratio of a MgZnphase in a range of 15% to 60% in a cross section in a thickness direction, and the MgZnphase includes a Ca-based intermetallic compound having a circle equivalent diameter of 0.10 μm or smaller.

Hot-dip Zn-based plated steel sheet

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/μmor more, a number density of coarse granular oxides in the internal oxidation layer being 4.0/25 μmor 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≥0.05% 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.

Steel sheet and plated steel sheet

The hot-dip plated steel material includes a steel material and a hot-dip plated layer disposed on a surface of the steel material, the hot-dip plated layer has a certain chemical composition, and the hot-dip plated layer has a diffraction intensity obtained from a result of X-ray diffraction measurement, the diffraction intensity satisfying a certain relationship.

Hot-dip plated steel material

A plated steel sheet for automobile structural members has a steel sheet, a plating layer formed on at least a part of a surface of the steel sheet, and an oxide layer formed on at least a part of a surface of the plating layer, the plating layer has a predetermined chemical composition, and when measurement by XPS is performed at a position 5.0 nm below a surface of the oxide layer in a thickness direction, I/I, which is the ratio of a maximum detected intensity of Mg to a maximum detected intensity of an oxide or hydroxide of Mg, is 0.00 or greater and 1.20 or less.

Plated steel sheet for automobile structural members

A plated steel material having a plating layer having an average chemical composition containing, in mass %, Zn: more than 50.00%, Al: more than 15.0% and less than 30.0%, Mg: more than 5.0% and less than 15.0%, and Si: 0.25% or more and less than 3.50%, and impurities, and wherein a total amount (ΣA) of at least one selected from the group consisting of Sn, Bi and In is less than 1.00%, a total amount (ΣB) of at least one selected from the group consisting of Ca, Y, La, Ce and Sr is 0.02% or more and less than 0.60%, 2.0≤SMg/Si<20.0 (Formula 1), 3.0≤Si/ΣB<24.0 (Formula 2), and 26.0≤(Si/ΣB)×(Mg/Si)<375.0 (Formula 3) are satisfied, and in an X-ray diffraction pattern of the surface of the plating layer, a diffraction intensity ratio R1 defined by R1={I(16.18°)+I(32.69°)}/I(27.0°) (Formula 4) satisfies 2.5<R1 (Formula 5) is used.

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Tokyo, Japan

Takuya Mitsunobu