Nippon Steel Corporation

Nippon Steel & Sumitomo Metal Corporation

Hiroshi Takebayashi

Masahiro Nakata

Takuya Mitsunobu

Takehiro Takahashi

Kohei Tokuda

Jun Maki

Akihiro Sengoku

Daisuke Maeda

Mamoru Saito

Masaaki Uranaka

Yasuto Goto

Yasuaki Tanaka

Takuya Nishio

Nobusato Kojima

Toshiki Nonaka

Mitsuru Yoshida

Toshiro Tomida

Jun Haga

Kenichiro Matsumura

Masayuki Wakita

Hidetoshi Shindo

Toyomitsu Nakamura

Norio Imai

Koji Akioka

Tamotsu Toki

Keitaro Matsuda

Kengo Hata

Kojiro Akiba

Suguhiro Fukushima

Kouichi Okamoto

Koji Kawanishi

Fumiaki Nakamura

Yuto Fukuda

Makoto Akahoshi

Yasuhiro Majima

Naoyuki Yamato

Shota Hayashida

Yoshitaka Soga

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 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

A plated steel sheet comprises a plated layer on a surface of a steel sheet, in which in the plated layer, the total amount ΣA of Sn, Bi, and In is less than 0.75%, the total amount ΣB of Ca, Y, La, and Ce is 0.03 to 0.60%, the total amount ΣC of Cr, Ti, Ni, Co, V, Nb, Cu, and Mn is 0 to 1.00%, Sn≤Si, and 20.0≤Mg/Si are satisfied, and in an X-ray diffraction pattern of a surface of the plated layer, an X-ray diffraction peak of AlZnCa, an X-ray diffraction peak of CaZn, and an X-ray diffraction peak of η'-MgZnsatisfy a predetermined relationship.

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 present invention relates to a plated steel sheet for hot stamping comprising a steel sheet and a Zn—Ni plating layer formed on at least one surface of the steel sheet, wherein the Zn—Ni plating layer has an Ni concentration of 8 mass % or more, a plating deposition amount of 10 g/mor more and 90 g/mor less per surface, and an average grain size of 50 nm or less.

Plated steel sheet for hot stamping

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

The present invention relates to a plated steel sheet for hot stamping comprising a steel sheet and a Zn—Ni plating layer formed on at least one surface of the steel sheet, wherein the Zn—Ni plating layer has an Ni concentration of 8 mass % or more, a plating deposition amount of 10 g/mor more and 90 g/mor less per surface, and an average grain size of 50 nm or more, and a difference between a diffraction peak of the Zn—Ni plating layer after heat treating the plated steel sheet for hot stamping at 200° C. for 1 hour, and a diffraction peak of the Zn—Ni plating layer before heat treating it, is 0.3° or less.

A plated steel sheet includes: a steel sheet; and a plating layer that is formed on at least a part of a surface of the steel sheet, in which a chemical composition of the plating layer includes, b mass %, Al: 6.00% to 35.00 %, Mg: 3.00% to 15.00%, La+Ce: 0.0001% to 0.5000% in total, and Zn, and in a surface of the plating layer, the area ratio of a lamellar structure in which an (Al—Zn) phase and a MgZnphase are arranged in layers is 10% to 95%, the lamellar spacing of the lamellar structure is 2.5 μm or less, and the area ratio of an (Al—Zn) dendrite is 10% or less.

A hot stamped steel includes a base material, a plated layer that is formed on a surface of the base material, and an oxide film 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, 0 to 0.50 mass % of Sb, 0 to 0.50 mass % of Pb, 0 to 1.00 mass % of Cu, 0 to 1.00 mass % of Sn, 0 to 1.00 mass % of Ti, 0 to 0.50 mass % of Sr, 0 to 1.00 mass % of Cr, 0 to 1.00 mass % of Ni, and 0 to 1.00 mass % of Mn with a remainder of Zn and impurities; and chemical composition of the oxide film contains 20.0 to 55.0 at % of Mg, 0.5 to 15.0 at % of Ca, 0 to 15.0 at % of Zn, and 0 at % or more and less than 10.0 at % of Al with a remainder of O and a total of 5.0 at % or less of impurities, and the adhesion amount of the oxide film per one surface is in a range of 0.01 to 10 g/m.

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Tokyo, Japan

Hiroshi Takebayashi