Abstract: After low-temperature finish rolling has been performed on a steel material having a certain chemical composition, cooling is performed at an average cooling rate of 10° C./s or higher to a temperature of 500° C., rapid cooling is further performed in a temperature range from a Ms temperature to a temperature of (Ms temperature-200° C.), coiling is thereafter performed in a low temperature range of 250° C. or lower, and the coiled steel sheet is uncoiled and further subjected to rolling with a certain amount or more of rolling load per unit width and the like. Consequently, it is possible to obtain a high-strength hot-rolled steel sheet having a microstructure including, in terms of area fraction, 95% or more of a martensite phase at a position located at ¼ of the thickness of the steel sheet, in which an average aspect ratio of prior austenite grains is 3.0 or more.

Abstract: A steel sheet is disclosed. A related member, and methods for manufacturing them are also disclosed. The steel sheet has a specific chemical composition and a specific steel microstructure and is such that the total area fraction of quenched martensite and retained austenite each having an aspect ratio of 3 or less and an equivalent circular diameter of 2.0 ?m or more is 20% or less relative to the total area fraction of quenched martensite and retained austenite, and the area fraction of a C-enriched region with a C concentration of 0.5 mass % or more (Sc?0.5) is 20% or less relative to the entire microstructure.

Abstract: The high-strength steel sheet has a chemical composition with MSC value in the range of 2.7% to 3.8% by mass defined by a specific formula, wherein the high-strength steel sheet has a microstructure including specific microstructures in a surface layer region extending from the surface of the steel sheet to a depth of 100 ?m and in an inner region other than the surface layer region. The high-strength steel sheet has the maximum height of the surface roughness of 30 ?m or less, a tensile strength of 980 MPa or more, a uniform elongation of 6% or more, and a ratio of 107-cycle plane bending fatigue strength to tensile strength (fatigue limit ratio) of 0.45 or more.

Abstract: Provided is a steel sheet having a chemical composition with Si content of 1.0 mass % or less, where there is little concern about LME cracking, that simultaneously achieves a TS of 1470 MPa or more, excellent formability, and excellent delayed fracture resistance. The steel sheet has a defined chemical composition, a complex microstructure consisting mainly of martensite and bainite, the maximum size of carbides inside martensite is 400 nm or less, a number density of bainite is 120×10?4/?m2 or more, and a number ratio of bainite having an aspect ratio of 1.8 or more is 60% or more.

Abstract: Provided is a steel sheet that simultaneously achieves a strength of TS: 1310 MPa or more and excellent formability. The steel sheet has a defined chemical composition and a complex structure consisting mainly of martensite and bainite, where carbides in the grains of martensite and bainite are 5% or more and 25% or less, and the dispersion interval of carbides satisfies Expression (1).

Abstract: Provided is a steel sheet that simultaneously achieves a strength of TS: 1310 MPa or more and excellent delayed fracture resistance. The steel sheet has a defined chemical composition and a complex structure consisting mainly of martensite and bainite, where carbides in the grains of martensite and bainite are 5% or more and 25% or less, the average circle equivalent diameter of carbides is 10 nm or more and 80 nm or less, and the particle size distribution of carbides satisfies Expression (1).

Abstract: A high-strength hot-rolled steel sheet according to the present invention has a specific chemical composition and a steel microstructure including, as main phases, 80% to 100% of martensite and bainite in terms of total area fraction. An entire area fraction of the martensite dispersed in the bainite is 2% to 20%. Among the martensite dispersed in the bainite, an area fraction of martensite each having an orientation difference of less than 15° between a crystal orientation of the martensite and a crystal orientation of at least one of bainite adjacent to the martensite is 50% or more relative to the whole martensite dispersed in the bainite.

Abstract: A high-strength hot-rolled steel sheet according to the present invention has a specific chemical composition and a steel microstructure including, as main phases, 80% to 100% of martensite and bainite in terms of total area fraction. An entire area fraction of the martensite dispersed in the bainite is 2% to 20%. Among the martensite dispersed in the bainite, an area fraction of martensite each having an orientation difference of 15° or more between a crystal orientation of the martensite and a crystal orientation of at least one of bainite adjacent to the martensite is more than 50% relative to the whole martensite dispersed in the bainite. When regions surrounded by boundaries between adjacent crystals having an orientation difference of 15° or more are defined as crystal grains, an average aspect ratio of the crystal grains present in a region extending from a surface of the steel sheet to a depth of 5 ?m is 2.0 or less.

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: 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: 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: The high-strength steel sheet has a chemical composition with MSC value in the range of 2.7% to 3.8% by mass defined by a specific formula, wherein the high-strength steel sheet has a microstructure including specific microstructures in a surface layer region extending from the surface of the steel sheet to a depth of 100 ?m and in an inner region other than the surface layer region. The high-strength steel sheet has the maximum height of the surface roughness of 30 ?m or less, a tensile strength of 980 MPa or more, a uniform elongation of 6% or more, and a ratio of 107-cycle plane bending fatigue strength to tensile strength (fatigue limit ratio) of 0.45 or more.

Abstract: There are provided an image display device, a display control method, and a cradle that are capable of adjusting display image quality with a simple configuration. An image display device according to the present embodiment includes a tablet terminal having a display, a cradle holding the tablet terminal, and an optical sensor provided on the cradle and capable of receiving display light from the display.

Abstract: After low-temperature finish rolling has been performed on a steel material having a certain chemical composition, cooling is performed at an average cooling rate of 10° C./s or higher to a temperature of 500° C., rapid cooling is further performed in a temperature range from a Ms temperature to a temperature of (Ms temperature - 200° C.), coiling is thereafter performed in a low temperature range of 250° C. or lower, and the coiled steel sheet is uncoiled and further subjected to rolling with a certain amount or more of rolling load per unit width and the like. Consequently, it is possible to obtain a high-strength hot-rolled steel sheet having a microstructure including, in terms of area fraction, 95% or more of a martensite phase at a position located at ¼ of the thickness of the steel sheet, in which an average aspect ratio of prior austenite grains is 3.0 or more.

Abstract: There are provided an image display device, a display control method, and a cradle that are capable of adjusting display image quality with a simple configuration. An image display device according to the present embodiment includes a tablet terminal having a display, a cradle holding the tablet terminal, and an optical sensor provided on the cradle and capable of receiving display light from the display.

Abstract: Provided are a hot-rolled steel sheet for coiled tubing and a method for manufacturing the steel sheet. The steel sheet has a yield strength of 480 MPa or more, a tensile strength of 600 MPa or more, a yield-strength difference (?YS) of 100 MPa or more, where the yield-strength difference is defined as a difference in yield strength between before and after a prestrain-heat treatment performed for simulation of a tube-making process and a stress-relief annealing heat treatment which are currently implemented, and a yield strength of 620 MPa or more after the prestrain-heat treatment.

Abstract: A hot-rolled steel plate has a predetermined chemical composition and a microstructure. In the microstructure, in a plate thickness 1/2 position, an area fraction of martensite is less than 3%, an area fraction of bainitic ferrite is 95% or greater, the bainitic ferrite has an average grain diameter of 6.0 ?m or less, an amount of Nb precipitated as Nb carbonitride is 0.025 mass % or greater, and an amount of Nb precipitated as Nb carbonitride having a grain diameter of 20 nm or greater constitutes 50% or greater of a total mass of the Nb precipitated as Nb carbonitride. The hot-rolled steel plate has a tensile strength of 640 MPa or greater, a yield ratio of 85% or less, a Charpy impact absorbed energy at ?40° C. of 300 J or greater, and a percent ductile fracture (SA value) of 85% or greater as determined by a DWTT test at ?40° C.

Abstract: A steel plate for high-strength and high-toughness steel pipes has a chemical composition containing, by mass %, C: 0.03% or more and 0.08% or less, Si: more than 0.05% and 0.50% or less, Mn: 1.5% or more and 2.5% or less, P: 0.001% or more and 0.010% or less, S: 0.0030% or less, Al: 0.01% or more and 0.08% or less, Nb: 0.010% or more and 0.080% or less, Ti: 0.005% or more and 0.025% or less, and N: 0.001% or more and 0.006% or less, and further containing, by mass %, at least one selected from Cu: 0.01% or more and 1.00% or less, Ni: 0.01% or more and 1.00% or less, Cr: 0.01% or more and 1.00% or less, Mo: 0.01% or more and 1.00% or less, V: 0.01% or more and 0.10% or less, and B: 0.0005% or more and 0.0030% or less, with the balance being Fe and inevitable impurities. The steel plate has a microstructure in which an area fraction of ferrite at a ½ position of a thickness of the steel plate is 20% or more and 80% or less and deformed ferrite constitutes 50% or more and 100% or less of the ferrite.

Abstract: Provided are a hot-rolled steel sheet for coiled tubing and a method for manufacturing the steel sheet. The steel sheet has a yield strength of 480 MPa or more, a tensile strength of 600 MPa or more, a yield-strength difference (AYS) of 100 MPa or more, where the yield-strength difference is defined as a difference in yield strength between before and after a prestrain-heat treatment performed for simulation of a tube-making process and a stress-relief annealing heat treatment which are currently implemented, and a yield strength of 620 MPa or more after the prestrain-heat treatment.