Nippon Steel Patente

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A threaded connection (100) includes a pin (10) and a box (20). The pin (10) includes a pin sealing surface (12) and a tapered male thread part (13). The tapered male thread part (13) includes male thread parts (131, 132). The first male thread part (131) is disposed at a position closer to a pipe body (31) than the pin sealing surface (12). The second male thread part (132) is disposed at a position closer to the pipe body (31) than the first male thread part (131). The box (20) includes a box sealing surface (22) and a tapered female thread part (23). The tapered female thread part (23) includes female thread parts (231, 232). The first male thread part (131) and the first female thread part (231) have a first taper ratio (T1). The second male thread part (132) and the second female thread part (232) have a second taper ratio (T2), which is smaller than the first taper ratio (T1).

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The present invention has as its technical concern the suppression of intergranular cracking (nitriding resistance) and suppression of formation of red iron oxide (oxidation resistance) in the 500 to 700°C medium and high temperature regions even in a gas atmosphere containing nitrogen and water vapor such as ammonia combustion gas and has as its object the provision of such a ferritic stainless steel. The present invention has a predetermined chemical composition giving a nitriding tendency index of 5 or less while polishes the steel product surface to introduce dislocations (strain), cause the steel product surface to harden, and make the difference in surface hardness and steel product center part hardness 25 Hv or more, whereby a strong Cr-Si-based oxide film strong in a 500°C or more atmosphere is formed at the surface layer and excellent oxidation resistance and nitriding resistance are obtained. Nitriding tendency index: 10Al+2Mo+3Ti+0.5Cu-1.5Si

There is provided a carbide molded body formed by molding carbide granules together with a binder, in which carbides in the carbide molded body satisfy (a) and (b): (a) a maximum particle size is less than one-half of a representative length d of the carbide molded body; and (b) when the carbides are classified into 70 vol% on a large-particle side and 30 vol% on a small-particle side, a ratio of a median particle size D50 of the carbides on the large-particle side to the median particle size D50 of the carbides on the small-particle side is from1.5 to 2.3. There is provided a method for producing the carbide molded body, the method including subjecting a carbide raw material to sieving treatment and crushing treatment such that the carbide granules have a particle size distribution the same as described in the above (a) and (b).

A laser processing device includes a gas injection unit that injects a gas from an opening toward an irradiation region of laser light on a surface of a steel sheet, the gas injection unit having a nozzle unit that includes an outer surface with a slope inclined so as to approach a center of the opening from an outer side of the opening in a direction parallel to the surface of the steel sheet on progression from a side opposite to the opening toward an opening side in an injection direction, in which a first adhesion inhibiting unit for inhibiting adhesion of laser spatter is disposed on at least a part of the outer surface of the nozzle unit.

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The present invention provides a high strength steel sheet excellent in appearance after molding and workability during molding through a novel configuration. A steel sheet according to the present invention has a specific chemical composition, and is characterized in that: when an area ratio of a hard phase in a region having a depth from the position corresponding to 3/8 the sheet thickness to the position corresponding to 5/8 the sheet thickness is Vm, an area ratio of the hard phase in a region having a depth from the surface of the steel sheet to the position corresponding to 1/8 the sheet thickness is 0.20 Vm to 0.80 Vm; the metal structure in the region having a depth from the position corresponding to 3/8 the sheet thickness to the position corresponding to 5/8 the sheet thickness contains 75-97% of ferrite and 3-25% of hard phase in area %; and the standard deviation of the area ratio of the hard phase in a direction orthogonal to the rolling direction and the sheet thickness direction in the region having a depth from the position corresponding to 3/8 the sheet thickness to the position corresponding to 5/8 the sheet thickness is 0.85% or less.

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[SUMMARY][PROBLEM] To provide a surface-treated member using a zinc-based plated steel material capable of exhibiting excellent corrosion resistance even in concrete.[SOLUTION] In a surface-treated member of the present invention, an exposure region having a base steel exposure portion is present in at least part of a zinc-based plating layer, and when each cross section obtained by cutting the exposure region in a thickness direction of a steel material is observed with a microscope, a length in a width direction, of each of the base steel exposure portions present is within a range of 1 to 100 µm, the number of the base steel exposure portions present per unit length is within a range of 3 to 20/mm, and a total length in the width direction, of the base steel exposure portions per unit length is 600 µm/mm or less. Further, a total area of regions each giving a cross section where the total length in the width direction, of the base steel exposure portions, per unit length is 600 µm/mm or less in a plan view from above is 0.7% or more of a surface area of the steel material in a plan view.

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A spot-welded member according to one aspect of the present disclosure includes: a first metal sheet and a second metal sheet disposed on surfaces of the spot-welded member and a first internal metal sheet group including one or more internal metal sheets disposed therebetween; a first spot weld joining the first metal sheet and the first internal metal sheet group; and a second spot weld joining the second metal sheet and the first internal metal sheet group, in which an indentation of the first spot weld is provided on the first metal sheet and the internal metal sheet, an indentation of the second spot weld is provided on the first metal sheet and the second metal sheet, and the indentation of the first spot weld is spaced apart from the indentation of the second spot weld, and the first nugget is spaced apart from the second metal sheet and the second nugget is spaced apart from the first metal sheet.

[PROBLEM] There is provided a surface-treated member that exhibits excellent corrosion resistance even in the soil at a depth of about several centimeters from the soil surface. [SOLUTION] The surface-treated member of the present invention is formed of a surface-treated steel material including: a steel material serving as a base material; and zinc-based coatings layers, a steel base exposed portion is present in at least a portion of the zinc-based coatings layer, in a case where a cross section obtained by cutting the steel base exposed portion in the thickness direction of the steel material according to the shape of the steel base exposed portion when the zinc-based coatings layer is viewed in plan from above is observed with a microscope, at least one or more cross sections each having a steel base exposure ratio falling within a range of 1.0 to 40.0% are present, in the cross section having the steel base exposure ratio falling within a range of 1.0 to 40.0%, the shortest distance from any point on the surface of the exposed steel material to the zinc-based coatings layer is greater than 0 µm and 50.0 µm or less, and the total area of regions where a cross section having the steel base exposure ratio being greater than 40.0% is given is 5.0% or less relative to the entire area of the steel base exposed portion.

A solid wire for gas-shielded arc welding according to an embodiment of the present disclosure includes: in terms of mass% with respect to a total mass of the solid wire, C: 0.04 to 0.12%, Si: 0.13 to 0.28%, Mn: 1.4 to 2.3%, Ti: 0.13 to 0.25%, Al: 0.001 to 0.050%, and the like, wherein Si × Mn ≤ 0.60, (Si + Mn/5)/(Ti + Al) ≤ 4.0, 1.00 ≤ Si + 0.5 × (Mn + Cr) + 0.3 × Ni, 0.30 ≤ C + Mn/6 + Si/24 + Ni/40 + Cr/5 + Mo/4 + V/14 ≤ 0.55, and 0 ≤ Cr + Ni ≤ 3.00 are satisfied.

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An austenitic stainless steel material that has high strength and has excellent hydrogen embrittlement resistance in a high-pressure hydrogen gas environment is provided. An austenitic stainless steel material of the present disclosure has a chemical composition consisting of, in mass%, C: 0.100% or less, Si: 1.000% or less, Mn: 8.00 to 20.00%, P: 0.050% or less, S: 0.0050% or less, Cr: 18.00 to 30.00%, Ni: 10.00 to 25.00%, N: 0.700 to 1.000%, V: 0.010 to 0.200%, Nb: 0.010 to 0.300%, Al: 0.200% or less, and O: 0.0100% or less, with the balance being Fe and impurities, in which Fnl defined by Formula (1) in the description is 18.0 or more when the content of Ni is less than 17.00% and is 22.0 or more when the content of Ni is 17.00% or more.

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A method for manufacturing a metal can (30) includes a step of preparing a material can (20) and a step of obtaining the metal can (30) by reshaping the material can (20) using a die set (10) including dies (11, 12, 13). The material can (20) includes a peripheral wall (21) including side walls (211, 212) and a bottom wall (22). In the step of reshaping the material can (20), the die (13) is pressed into a space between the dies (11, 12) disposed inside the material can (20) to move the dies (11, 12) away from each other, and side surfaces (113, 123) of the dies (11, 12) are brought into contact with the side walls (211, 212), respectively, to increase the width between the side walls (211, 212). The side surfaces (113, 123) are each formed such that a portion on the opening (23) side is positioned outward of a portion on the bottom wall (22) side in a direction in which the dies (11, 12) move away from each other.

An austenitic stainless steel material that has high strength and has excellent hydrogen embrittlement resistance in a high-pressure hydrogen gas environment is provided. An austenitic stainless steel material of the present disclosure has a chemical composition consisting of, in mass%, C: 0.100% or less, Si: 1.000% or less, Mn: 8.00 to 20.00%, P: 0.050% or less, S: 0.0050% or less, Cr: 18.00 to 30.00%, Ni: 10.00 to 25.00%, N: more than 0.350 to less than 0.700%, V: 0.010 to 0.200%, Nb: 0.010 to 0.300%, Al: 0.200% or less, and O: 0.0100% or less, with the balance being Fe and impurities, in which Fn1 defined by Formula (1) in the description is 18.0 or more when the content of Ni is less than 17.00% and is 22.0 or more when the content of Ni is 17.00% or more. In the steel material, a number density of (Cr, Nb) composite precipitates having an equivalent circular diameter of 50 to 500 nm is 1.00 /µm<2> or more.

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