JFE Steel Patente

Provided is a method of operating a direct reduction furnace that reduces CO<2> emissions and enables stable operation by avoiding problems such as reduced productivity and shutdown of operations. A high-temperature gas is injected into the direct reduction furnace separately from the reducing gas, and the vertical injection position of the high-temperature gas is set higher than the vertical injection position of the reducing gas.

Provided is a rolled material warp amount measurement technology that can accurately measure a warp amount of a rolled material. This rolled material warp amount measurement method measures a warp amount of a rolled material before and after a rolling mill in a hot rolling line. In this method, using a camera capable of measuring brightness in a wavelength range from visible light to near-infrared light, an image of the rolled material after rolling is taken from an obliquely upper side of the rolled material; the image taken of the rolled material is input into a warp measurement model created beforehand by machine learning, and a region in which a sheet width narrows at leading and tail end portions of the rolled material is estimated; a measurement image region to be used for measurement of the warp amount is determined; a sheet-width edge portion of the rolled material is detected based on a brightness value of the image of the rolled material present in the measurement image region; the image of the rolled material is divided along a rolling direction of the rolled material; the shape of the sheet-width edge portion in each segment of the divided image is quadratically approximated; and the warp amount of the rolled material is quantified as a curvature or a warp height based on the quadratically approximated shape of the sheet-width edge portion.

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Provided is a method capable of stably and productively producing a grain-oriented electrical steel sheet with excellent magnetic properties when performing cold rolling using a single-stand rolling mill. Specifically, provided is a cold rolling method for a grain-oriented electrical steel sheet, including, in forming a cold-rolled sheet with a final thickness by performing cold rolling with the total rolling reduction rate set to 80% or higher, dividing the cold rolling into first-stage cold rolling and second-stage cold rolling; performing, during the first-stage cold rolling, cold rolling using a tandem rolling mill to obtain an intermediate thickness; and performing, during the second-stage cold rolling, cold rolling through one to three passes using a single-stand rolling mill, with the ratio of the work roll diameter of the single-stand rolling mill to the work roll diameter of the final stand of the tandem rolling mill used in the first-stage cold rolling set in the range of 0.30 to 0.95, to obtain a final thickness following the intermediate thickness, thereby achieving the best value of the magnetic flux density B<8> of the resulting product sheet in the sheet width direction of 1.920 T or higher. Also provided are a method for producing a grain-oriented electrical steel sheet using the cold rolling method, and a cold rolling equipment line used for the cold rolling.

Provided is a method capable of stably and productively producing a grain-oriented electrical steel sheet with excellent magnetic properties when performing cold rolling using a single-stand rolling mill. Specifically, provided is a cold rolling method for a grain-oriented electrical steel sheet, including, in forming a cold-rolled sheet with a final thickness by performing cold rolling with the total rolling reduction rate set to 80% or higher, dividing the cold rolling into first-stage cold rolling and second-stage cold rolling; performing, during the first-stage cold rolling, cold rolling using a tandem rolling mill to obtain an intermediate thickness; and performing, during the second-stage cold rolling, cold rolling through one to three passes using a single-stand rolling mill, with the ratio of the work roll diameter of the single-stand rolling mill to the work roll diameter of the final stand of the tandem rolling mill used in the first-stage cold rolling set in the range of 0.60 to 1.35, to obtain a final thickness following the intermediate thickness, thereby achieving the difference between the maximum value and the minimum value of the magnetic flux density B₈ of the resulting product sheet in the sheet width direction of 0.005 T or less. Also provided are a method for producing a grain-oriented electrical steel sheet using the cold rolling method, and a cold rolling equipment line used for the cold rolling.

A detection device according to the present invention is a detection device for determining whether or not a determination target image is a detection target image including a detection target object. The detection device includes an image restoration and generation unit configured to generate a non-detection target image corresponding to the determination target image by inputting data of the determination target image to a learning model in which data of a processed image is input data and data of a non-detection target image not including the detection target object according to the processed image is output data, a difference calculation unit configured to generate a difference image between the determination target image and the non-detection target image generated by the image restoration and generation unit, and a detection unit configured to determine whether or not the determination target image is the detection target image based on the difference image generated by the difference calculation unit.

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Provided are a zinc or zinc alloy coated or plated steel sheet having excellent delayed fracture resistance in stretch flanged areas, and a method of producing same. The zinc or zinc alloy coated or plated steel sheet includes a base steel sheet and a zinc or zinc alloy coated or plated layer formed on the surface of the base steel sheet. The base steel sheet has a defined chemical composition. The base steel sheet has a defined microstructure at a 1/4 sheet thickness position. A thickness of a carbon concentration reduced portion in the surface layer of the base steel sheet is 1.0 µm or more and 150.0 µm or less. A thickness of a bainite precipitation region directly below the carbon concentration reduced portion is 10 µm or more. A total coverage of retained austenite and fresh martensite at prior austenite grain boundaries directly below the carbon concentration reduced portion is 30.0 % or more and 60.0 % or less. A carbon concentration of retained austenite covering the prior austenite grain boundaries is less than 0.60 mass%. The tensile strength is 1470 MPa or more.

A material quality estimation model generation method includes: a material quality estimation base model generating step of performing, by a model generation unit of a computer, machine learning using existing manufacturing condition data as an input and existing quality data associated with the existing manufacturing condition data as an output to generate a material quality estimation base model; and a material quality estimation model relearning step of performing, by the model generation unit, relearning of the material quality estimation base model using additional manufacturing condition data as an input and additional quality data associated with the additional manufacturing condition data as an output to generate a material quality estimation model.

This quality defect diagnostic device comprises: a data division unit for dividing product data to be diagnosed in a two-dimensional manner into prescribed blocks; a data aggregation unit for extracting operation data and facility maintenance data for each pre-established classification of quality defects on the basis of the tendency of occurrence of quality defects in the post-division blocks, and aggregating the extracted operation data and facility maintenance data for each region including two or more blocks in a specific direction of the product; and a quality defect determination unit for determining whether a quality defect has occurred by using a plurality of prediction models that are created for each classification of quality defects and are trained on the relationship between quality data and the post-aggregation operation data and facility maintenance data.

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A control method for a blast furnace according to the present invention includes a temperature distribution estimation step of estimating a temperature distribution at a bottom of a blast furnace by performing heat transfer analysis by using a numerical model of the blast furnace, a determination step of determining a risk of generating a region of poor hot metal flow at the bottom of the blast furnace based on a difference value between the temperature distribution estimated in the temperature distribution estimation step and an actual measurement value of temperature at the bottom of the blast furnace, and a control step of controlling an operating condition of the blast furnace so that the region of poor hot metal flow is not generated, based on a result of the determination in the determination step.