Abstract: A hot-pressed member having excellent bending collapsibility, a method for manufacturing the same, and a method for manufacturing a steel sheet for the hot-pressed member. The hot-pressed member includes a steel sheet as a base material, the steel sheet having a specified chemical composition. The hot-pressed member has a microstructure in which a martensite microstructure is present in a volume fraction of 70% or greater, and a number density of inclusions having a longest diameter of 25 ?m or greater is 0.02/mm2 or less. The hot-pressed member has a tensile strength of 1.8 GPa or greater.

Abstract: A high-strength galvanized steel sheet of the present invention includes a steel sheet having a specific chemical composition, and a steel structure containing, in terms of area ratio, 4% or more and 20% or less of retained austenite, 30% or less (including 0%) of ferrite, 40% or more of martensite, and 10% or more and 50% or less of bainite; and a galvanized layer provided on the steel sheet, in which an amount of diffusible hydrogen in the steel is less than 0.20 mass ppm, a tensile strength is 1100 MPa or more, a relationship between a tensile strength TS (MPa), an elongation El (%), and a sheet thickness t (mm) satisfies a (1) formula below, and a yield ratio YR is 67% or more. TS×(El+3?2.

Abstract: A surface-treated steel sheet includes a chemical conversion coating with a thickness of 3.0 ?m or less, the chemical conversion coating being placed on a surface of a hot-dip Zn—Al alloy coated steel sheet including a hot-dip Zn—Al alloy coating film containing Al: more than 1.0 mass % and 15 mass % or less, a balance being Zn and inevitable impurities. The chemical conversion coating contains AlH2P3O10.2H2O and a compound containing one or more elements selected from Mg, Ca, and Sr such that a sum of contents of AlH2P3O10.2H2O and the compound is 3.0 mass % to 50 mass %.

Abstract: A flaw grinding system, a flaw grinding method, and a steel-product manufacturing method enable automation of the task of grinding a flaw on the surface of a workpiece having a three-dimensional shape, while also reducing the occurrence of faulty grinding such as over-grinding or under-grinding. The flaw grinding system includes a grinding apparatus, a shape measurement apparatus, a flaw detection apparatus, and a grinding-tool control apparatus. The grinding apparatus includes a grinding tool that grinds a flaw on a surface of a workpiece. The shape measurement apparatus measures a three-dimensional shape and an attitude of the workpiece. The flaw detection apparatus detects a location of the flaw on the workpiece. The grinding-tool control apparatus generates a trajectory of the grinding tool to grind the flaw. The grinding-tool control apparatus controls the grinding apparatus in a manner that causes the grinding tool to move along the trajectory.

Abstract: A refining process control device includes: a past similar performance extraction unit configured to extract, from the refining performance database, a performance value of a past refining process in which a refining condition being a refining process condition acquired before the start of the refining process and including a result of an immediately preceding refining process in the refining facility, is similar to a refining process condition as a calculation target and the evaluation value is high; and an operation amount determination unit configured to determine an initial operation amount at the start of a refining process based on the performance value of the past refining process extracted by the past similar performance extraction unit, and determine an operation amount based on a change amount of the initial operation amount after the start of the refining process.

Abstract: Disclosed is a method of producing a surface-treated steel sheet for organic resin coating comprising: applying, to a surface of a zinc or zinc alloy coated or plated steel sheet, a surface-treatment solution containing a resin compound having a specific bisphenol skeleton, a cationic urethane resin emulsion, a silane coupling agent having a specific reactive functional group, an organic titanium chelate compound, a tetravalent vanadium compound, a molybdate compound, a fluorine compound, and water in a specific ratio and with a pH of 4 to 5 to form a surface-treatment layer such that a coating weight of the surface-treatment layer per surface after drying of the surface-treatment solution is 0.005 g/m2 to 1.8 g/m2.

Abstract: A method of manufacturing a pressure accumulator, using an AE signal for the pressure accumulator, includes: a first estimation step of estimating with an AE sensor provided at the pressure accumulator, a range of stress levels at each of which a damage AE signal that is generated from the pressure accumulator because of damage of material of the pressure accumulator is in a predetermined state; and a first design step of designing the pressure accumulator such that a minimum thickness of the pressure accumulator is determined based on the stress level range estimated in the first estimation step.

Abstract: Provided is a hot-band annealing method comprising subjecting a Si-containing hot rolled steel sheet, having an oxidized scale formed on a surface of the steel sheet by hot rolling, to hot-band annealing with a hot-band annealing equipment provided with a heating zone, a soaking zone, a cooling zone, and a rapid heating device at an upstream side of the heating zone and/or in an inlet side of the heating zone, wherein the hot rolled steel sheet is heated by not lower than 50° C. at a heating rate of not less than 15° C./s by using the rapid heating device to improve a descaling property. Also, provided is a descaling method characterized by subjecting the Si-containing hot rolled steel sheet, after the hot-band annealing, to descaling only by pickling without requiring mechanical descaling or heating the steel sheet in the pickling process.

Abstract: A high-strength steel sheet includes a steel structure with: ferrite being 35% to 80% and tempered martensite being greater than 5% and 20% or less in terms of area fraction; retained austenite being 8% or more in terms of volume fraction; an average grain size of: the ferrite being 6 ?m or less; and the retained austenite being 3 ?m or less; a value obtained by dividing an area fraction of blocky austenite by a sum of area fractions of lath-like austenite and the blocky austenite being 0.6 or more; a value obtained by dividing, by mass %, an average Mn content in the retained austenite by an average Mn content in the ferrite being 1.5 or more; and a value obtained by dividing, by mass %, an average C content in the retained austenite by an average C content in the ferrite being 3.0 or more.

Abstract: A material characteristic value prediction system that can predict material characteristic values with high accuracy is provided. Also provided is a method of manufacturing a metal sheet that can improve the product yield rate, by changing manufacturing conditions of subsequent processes.

Abstract: Provided is a continuous hot-dip galvanizing apparatus comprising: a vertical annealing furnace having heating, soaking zone, and cooling zones therein; and a hot-dip galvanizing line downstream of the cooling zone. The heating, soaking, and cooling zones each have, in its upper portion, at least one upper hearth roll and, in its lower portion, at least one lower hearth roll. The soaking zone has a first and second humidified gas supply ports to supply a humidified gas having a dew point of 10° C. to 30° C. to the soaking zone. The first and second humidified gas supply ports are 1.0 m to 5.0 m lower than the center of the lower and upper hearth rolls, respectively, and overlap the steel sheet. The first humidified gas supply port is provided only for an ascending pass and the second humidified gas supply port is provided only for a descending pass.

Abstract: A method for preparing a coal, which is used alone or in combination with at least one other coal, or a caking additive as a raw material for coke production. The method includes, before the coal or caking additive is delivered to a coke plant, adjusting a grain size such that the amount of grains with a grain size of 6 mm or more in the coal or caking additive satisfies at least one of a degree of entanglement (a - b)/a of 0.20 or more and a portion having a height a of 30 mm or more is 30% or less by mass. The height a is a height of semicoke adhering to a stirrer, the semicoke formed by heating the coal or caking additive in a container while rotating the stirrer, and the height b is a height of the semicoke on an inner wall of the container.

Abstract: Provided is a powder for annealing separator that is used for a grain-oriented electrical steel sheet and enables obtainment of a grain-oriented electrical steel sheet having excellent magnetic properties as a result of favorable purification of impurities in steel. The powder for annealing separator contains magnesium oxide as a main component, and has a nitrogen gas permeability of 0.020 cm/s or more and 0.50 cm/s or less in a state of being applied between coiled steel sheets before start of secondary recrystallization.

Abstract: Provided is a steel strip that can provide accurate material information and a method of producing the same. A steel strip (9) comprises a medium that provides material information including a material distribution associating each position in a two-dimensional direction of a rolling direction and a transverse direction with a material characteristic value. The material information is predicted using a prediction model to which input data including a line output factor in a production line for the steel strip, a disturbance factor, and a component value of the steel strip being produced is input. The prediction model includes: a machine learning model that receives the input data as input and outputs a production condition factor and that is generated by machine learning; and a metallurgical model that receives the production condition factor as input and outputs the material characteristic value.

Abstract: To stably produce grain-oriented electrical steel sheets with excellent film properties and magnetic properties. A method of producing a grain-oriented electrical steel sheet of this disclosure comprises subjecting a steel slab containing predetermined additive elements to hot rolling; subjecting the hot-rolled sheet to cold rolling to have a final sheet thickness; subjecting the cold-rolled sheet to decarburization annealing; applying an annealing separator having MgO as a main component to the decarburization annealing sheet; and subjecting the decarburization annealing sheet to finish annealing. The main component of the annealing separator has a BET specific surface area ratio H2O/N2 of 0.6 to 1.6 and a percentage of particles with a particle size of 40 µm or more in a slurry state of 5 mass% or less.

Abstract: A grain-oriented electromagnetic steel sheet exhibits excellent magnetic characteristics and excellent coating film adhesion after strain relieving annealing. The grain-oriented electromagnetic steel sheet includes: a steel sheet; a coating film layer A that is a ceramic coating film which is formed on the steel sheet and has an oxide content of less than 30% by mass; and a coating film layer B that is an insulating tension coating film which is arranged on the coating film layer A and contains an oxide. The binding energy of the 1s orbital of oxygen in the coating film layer B is higher than 530 eV; and tension applied to the steel sheet by the coating film layer B per a thickness of 1.0 ?m of the coating film layer B is 4.0 MPa/?m or more.

Abstract: A chattering detection method for a cold rolling mill, the method including: measuring a vibration of a cold rolling mill; calculating a time waveform of vibration intensity by performing frequency analysis on a time waveform of the measured vibration of the cold rolling mill for a predetermined period equal to or shorter than a time in which a periodic vibration continues without converging; and detecting a chattering sign vibration of the cold rolling mill based on a number of points having vibration intensity values that exceed a predetermined threshold, the points being included in the calculated time waveform of the vibration intensity.

Abstract: A scrap discrimination system and a scrap discrimination method that can improve scrap discrimination technology are provided. A scrap discrimination system includes a scrap part extraction model (221) that extracts, based on a camera image, a scrap part located in a central portion included in the camera image with reference to a window (107) defined in advance in an image, a scrap discrimination model (222), generated by teacher data including training images, that sorts grades of scrap and a ratio of each grade from a scrap image extracted by the scrap part extraction model (221), and an output interface (24) that outputs information on the grades of scrap and the ratio of each grade as discriminated based on the scrap image using the scrap discrimination model (222).

Abstract: Provided are a method of predicting hydrogen content in steel of a steel strip etc. Provided is, in a continuous galvanizing line that performs manufacturing processes including an annealing process, a coating process, and a reheating process of a steel strip, a method of predicting hydrogen content in steel of a steel strip downstream of the reheating process, including acquiring at least one parameter selected from operation parameters of the continuous galvanizing line and transformation rate information measured in at least one of the annealing process and the reheating process as input data, and predicting hydrogen content in steel of a steel strip downstream of the reheating process using a prediction model of hydrogen content in steel that has been trained by machine learning and that outputs information on hydrogen content in steel of a steel strip downstream of the reheating process as output data.

Abstract: A steel pipe collapse strength prediction model generation method, a steel pipe collapse strength prediction method, a steel pipe manufacturing characteristics determination method, and a steel pipe manufacturing method capable of highly accurately predicting the collapse strength under external pressure bending of a coated steel pipe coated after steel pipe forming in consideration of the pipe-making strain during steel pipe forming and coating conditions as well as the bending strain during construction.