Abstract: A high-strength steel sheet is disclosed having a specified chemical composition and a steel microstructure composed of, on an area fraction basis, ferrite: 1% to 40%, fresh martensite: 1% to 20%, bainite and tempered martensite in total: 35% to 90%, and retained austenite: 6% or more, wherein a value obtained by dividing an average Mn content (% by mass) of the retained austenite by an average Mn content (% by mass) of the ferrite is 1.1 or more, and a value obtained by dividing an average C content (% by mass) of retained austenite with an aspect ratio of 2.0 or more by an average C content (% by mass) of the ferrite is 3.0 or more, and a value obtained by dividing a C content of all retained austenite by a C content of a T0 composition is 1.0 or more.

Abstract: A friction joining element for mechanically joining a sheet set prepared by stacking two or more metal sheets including a high strength steel sheet as an upper sheet. The friction joining element includes a mandrel having an overall length adjusted to be equal to or less than the total thickness of the sheet set, and a collar disposed at an upper portion of the mandrel. The friction joining element has a screw thread on a side surface of a head-side portion of the mandrel.

Abstract: A method for detecting abnormal vibration of a rolling mill including a collecting step of collecting vibration data of the rolling mill, a frequency analysis step of generating first analysis data by performing frequency analysis of the vibration data, a principal component analysis step of performing principal component analysis on the first analysis data by using reference data specified in advance on the basis of a normal state as a principal component and thereby generating evaluation data, which is a projection of the first analysis data onto the reference data, and an abnormal vibration detection step of extracting an outlier component from the evaluation data and the first analysis data and detecting an abnormality of the rolling mill from the extracted outlier component.

Abstract: A high-strength steel sheet is disclosed having a specified chemical composition and a steel microstructure composed of, on an area fraction basis, ferrite: 1% to 40%, fresh martensite: less than 1.0%, bainite and tempered martensite in total: 40% to 90%, and retained austenite: 6% or more, wherein a value obtained by dividing an average Mn content (% by mass) of the retained austenite by an average Mn content (% by mass) of the ferrite is 1.1 or more, and a value obtained by dividing an average C content (% by mass) of retained austenite with an aspect ratio of 2.0 or more by an average C content (% by mass) of the ferrite is 3.0 or more, and a diffusible hydrogen content of steel is 0.3 ppm by mass or less.

Abstract: A manufacturing method of a cold-rolled steel sheet in which the method uses a full-width heating device that heats a steel sheet over an entire area in a width direction of the steel sheet, an edge heating device that heats end portions in the width direction of the steel sheet, and a cold rolling mill that rolls the steel sheet and that is arranged on a downstream side in a rolling direction with respect to the full-width heating device and the edge heating device, the method includes: heating the steel sheet by using the full-width heating device and the edge heating device in such a manner that temperatures of the end portions in the width direction becomes higher than a temperature of a central portion in the width direction of the steel sheet on an entry side of the cold rolling mill.

Abstract: A hot-rolled steel sheet has a chemical composition containing, by mass %, C: 0.10% or less, Si: 2.0% or less, Mn: 2.0% or less, P: 0.100% or less, S: 0.02% or less, Al: 1.5% or less, and O: 0.0025% or less, the balance being Fe and incidental impurities, in which a main phase is ferrite, and a maximum orientation density of grains is 2.1 or less.

Abstract: When supplying oxygen source to molten pig iron inside a converter-type refining furnace and performing desiliconization, dephosphorization, and decarburization refining, one or more of slag removal flow shape, slag removal flow velocity, and slag surface shape while discharging slag through a throat is measured to estimate one or both of a slag removal amount and physical properties of removed slag. When sequentially performing one or both of desiliconization and dephosphorization, an intermediate step of discharging part or all of generated slag through the throat, and the remaining other refining step, in the intermediate step, the method measures one or two of slag removal flow shape, slag removal flow velocity, and slag surface shape, estimates one or both of amount and physical properties of slag removed, estimates remaining slag amount, or remaining slag amount and composition, and determines an auxiliary raw material amount to be fed in the other refining step.

Abstract: A high-strength hot-rolled steel sheet has a chemical composition containing, by mass %, C: 0.02% to 0.23%, Si: 0.10% to 3.00%, Mn: 0.5% to 3.5%, P: 0.100% or less, S: 0.02% or less, and Al: 1.5% or less, the balance being Fe and incidental impurities, in which the total area fraction of martensite and bainite is 80% to 100%, the maximum orientation density of grains is less than 2.5 in a region extending from a position of 5 ?m to a position of 10 ?m from a surface in the thickness direction, and the maximum orientation density of grains is 2.5 or more in a region extending from a position of 50 ?m to a position of 100 ?m from the surface in the thickness direction.

Abstract: Provided is a raw material particle for production of agglomerate that can be used to produce an agglomerate with better reducing performance than conventional agglomerates. The raw material particle 1(2) of the present disclosure is a raw material particle for producing an agglomerate as a raw material for producing reduced iron, including a central part 11(21), and a peripheral part 12(22) that covers the periphery of the central part 11(21). The central part 11 has a metal iron-containing substance, the central part 12 has a volatile substance, and the peripheral part 12(22) has iron oxide.

Abstract: Provided is a linear groove formation pattern with which both an effect of reducing the building factor and a high magnetic flux density can be obtained. In a grain-oriented electrical steel sheet having a plurality of linear grooves extending in a direction crossing a rolling direction of the steel sheet on a surface of the steel sheet, a surface of the steel sheet between the linear grooves has a recessed defect that is recessed from the surface, a volume fraction of the recessed defect in the steel sheet is 0.0025 vol % or more and 0.01 vol % or less of a steel sheet without the recessed defect, and discontinuous portions that disrupt the extension of the linear grooves are provided at a frequency of 30 or more and 200 or less per square meter of the steel sheet.

Abstract: To provide a steel sheet with a tensile strength of 1310 MPa or more that can achieve excellent press formability in a steel having a martensite-dominant microstructure with excellent delayed fracture resistance properties. Disclosed is a steel sheet including: a chemical composition containing, by mass %, C: 0.12-0.40%, Si: 1.5% or less, Mn: 1.7% or less, P: 0.05% or less, S: 0.010% or less, sol.Al: 1.00% or less, N: 0.010% or less, Ti: 0.002-0.080%, and B: 0.0002-0.0050%, with the balance being Fe and inevitable impurities; a metallic structure in which an area ratio of martensite to an entire microstructure is 95% or more, and a ratio LS/LB satisfies a predetermined formula (1), where LS denotes a length of a sub-block boundary and LB denotes a length of a block boundary; and a tensile strength of 1310 MPa or more.

Abstract: A clad steel plate having tensile strength (TS) of 780 MPa or more, excellent ductility, bendability, collision resistance, and LME resistance. The clad steel plate having a base metal and a cladding metal on front and back surfaces of the base metal, and the chemical composition and microstructure of the base metal and the cladding metal being appropriately controlled so that the average Vickers hardness (HVL) of the cladding metal is 260 or less, the average Vickers hardness (HVL) of the cladding metal divided by the average Vickers hardness (HVB) of the base metal is 0.80 or less, the boundary roughness between the base metal and the cladding metal is 50 ?m or less at the maximum height Ry, and the number of voids at the boundary between the base metal and the cladding metal is controlled to 20 or fewer per 10 mm length of the boundary.

Abstract: The high-strength steel sheet has a predetermined chemical composition and has a microstructure containing a specific microstructure in a surface layer region and in an inner region. The surface layer region has an average grain size of 6 ?m or less. A difference between a hardness of the surface layer region extending from the surface of the steel sheet to the position of one-tenth of the thickness of the steel sheet and a hardness of the inner region is 5% or more and 15% or less of [0.3×tensile strength (MPa)], and the steel sheet has a tensile strength of 980 MPa or more, a uniform elongation of 6% or more, and a ratio of a critical bending radius to a thickness of 1.5 or less.

Abstract: To provide continuous annealing equipment, a continuous annealing method, a method of producing cold-rolled steel sheets and a method of producing coated or plated steel sheets which enable a quick response to fluctuations in material properties and enable minimization of fluctuations in mechanical properties of products. The continuous annealing equipment is continuous annealing equipment for steel sheets including, in this order, a heating zone (6) and a soaking zone (7), the soaking zone (7) including a first soaking zone (7A) and a second soaking zone (7B) provided after the first soaking zone (7A), the continuous annealing equipment including: a first induction heating device (9) provided between first soaking zone (7A) and a second soaking zone (7B); and a measuring device (10) configured to measure austenite fractions of the steel sheets at an exit of the second soaking zone (7B).

Abstract: A life estimation apparatus for a pressure accumulator estimates the life of the pressure accumulator based on an AE signal for the pressure accumulator. The life estimation apparatus includes: an AE sensor that is provided at the pressure accumulator and detects the AE signal; and an estimation unit that sets a point of time at which the AE sensor detects a damage AE signal that is generated from the pressure accumulator because of damage of a material during use of the pressure accumulator, as a minimum initial flaw generation time point that is a point of time at which a minimum initial flaw of the pressure accumulator that is detected by a non-destructive inspection method is generated in shipping of the pressure accumulator.

Abstract: A collision resistance performance of a structural member is effectively improved while suppressing an unnecessary increase in mass of the structural member. The structural member includes a hollow member and a tension member. The hollow member forms a closed cross-sectional shape by a top sheet portion, a pair of sidewall portions each continuous to each side of the top sheet portion in a width direction, and a bottom sheet portion arranged to face the top sheet portion. The tension member is formed by a metal sheet extending along the width direction of the top sheet portion and being thinner than the sheet thickness of the hollow member, and connects inner surfaces of the pair of sidewall portions facing each other to each other to restrain the distance between the pair of sidewall portions from increasing.

Abstract: A grain-oriented electrical steel sheet for a wound transformer core. The steel sheet having a sheet thickness t, where t and an iron loss deterioration ratio obtained by subjecting the steel sheet under elliptic magnetization satisfy the following relations: (i) when t?0.20 mm, the iron loss deterioration ratio is 60% or less; (ii) when 0.20 mm<t<0.27 mm, the iron loss deterioration ratio is 55% or less; and (iii) when 0.27 mm?t, the iron loss deterioration ratio is 50% or less. The iron loss deterioration ratio is calculated from ((WA?WB)/WB)×100, where WA is iron loss under 50 Hz elliptic magnetization of 1.7 T in a rolling direction and 0.6 T in a direction orthogonal to the rolling direction, and WB is iron loss under 50 Hz alternating magnetization of 1.7 T in the rolling direction.

Abstract: An insulating coating treatment liquid for forming a chromium-free insulating coating on a surface of a grain-oriented electrical steel sheet, the insulating coating treatment liquid including at least one phosphate salt selected from phosphate salts of any of Mg, Ca, Ba, Sr, Zn, Al, and Mn and including colloidal silica and particles of a metal-element-containing compound. A content of the colloidal silica in terms of SiO2, on a solids basis, is 50 to 120 parts by mass, and a content of the particles of a metal-element-containing compound in terms of elemental metal is 5 to 60 parts by mass, per 100 parts by mass of the at least one phosphate salt, and the insulating coating treatment liquid has a thixotropic index (TI) of 1.00 or greater and 10.00 or less.

Abstract: A cold rolling mill rolling condition setting method using a prediction model being generated with an explanatory variable being first multi-dimensional data obtained by transforming past rolling performance data including pre-cold rolling data of a roll material on an entry side of the cold rolling mill into multi-dimensional data, and an objective variable being post-cold rolling data of the roll material on a delivery side of the cold rolling mill, the method includes: estimating a post-rolling shape of a roll target material by inputting, to the prediction model, second multi-dimensional data generated from information including the pre-cold rolling data of the roll target material on the entry side of the cold rolling mill and a target rolling condition of the cold rolling mill; and changing the target rolling condition of the cold rolling mill such that the estimated post-rolling shape of the roll target material satisfies a predetermined condition.

Abstract: A steel pipe for high-pressure hydrogen, the steel pipe having a chemical composition containing, by mass %, C: 0.05% to 0.60%, Si: 0.001% to 2.0%, Mn: 0.01% to 5.0%, P: 0.030% or less, S: 0.010% or less, N: 0.010% or less, Al: 0.0001% to 1.00%, 0: 0.010% or less, H: 0.00010% or less, and a balance of Fe and incidental impurities and a metallic microstructure including, in terms of area fraction, 3% or less (including 0%) of retained austenite, in which the number of inclusions having an aspect ratio of 2.0 or more and a length of 10 ?m or more is 15/100 mm2 or less.