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 1.6 ?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 15% or less relative to the entire microstructure.

Abstract: A steel sheet, a member, and methods for manufacturing the same, are provided. The steel sheet has excellent ductility, flangeability, and phosphatability, and a tensile strength of 780 MPa or more. The steel sheet has a chemical composition that contains, in mass %, C, Si, Mn, P, S, sol. Al, and N in predetermined ranges and that satisfies formula (1), and has a steel microstructure having area fractions of polygonal ferrite and so forth within predetermined ranges, in which the maximum concentration of P [Pm] within 1 ?m from the surface of the steel sheet in the thickness direction is 0.025 mass % or more, and formula (2) below is satisfied: [ Si ] / [ M ? n ] ? 0.35 formula ? ( 1 ) [ Pm ] / [ P ] ? 1.5 .

Abstract: A steel sheet, a member, and methods for producing the same, are disclosed. The steel sheet has a chemical composition with specified C, Si, Mn, P, S, sol. Al, and N contents and has a steel microstructure containing, in area fractions, a microstructure composed of at least one of ferrite and bainitic ferrite: 10% or more and 60% or less, a microstructure composed of at least one of tempered martensite and lower bainite: 20% or more and 80% or less, retained austenite: 5% or more, and fresh martensite: 10% or less. The average C concentration in the retained austenite is 0.60 mass % or more. In a region within 100 ?m from a steel sheet surface in a thickness direction, a content of Fe element present as carbides in the tempered martensite is 0.20 mass % or less on average.

Abstract: Provided is a steel sheet that has a TS of 1180 MPa or more, high EL, and also excellent toughness and crash properties after paint baking. The steel sheet has a defined chemical composition and a microstructure where an area fraction of tempered martensite is 83% or more, an area fraction of retained austenite is less than 3%, a total area fraction of bainitic ferrite and ferrite 5 % or more and less than 15%, and a 20° or greater grain boundary density in tempered martensite is 1.0 ?m/?m2 or more, satisfying the following Expression ? ( 1 ) ? KAM ? ( S ) / KAM ? ( C ) > 1.

Abstract: Provided is a steel sheet that has a TS of 1320 MPa or more, as well as excellent stretch flangeability, and excellent toughness and crash properties after paint baking. The steel sheet has a defined chemical composition and a microstructure where an area fraction of tempered martensite is 95% or more, an area fraction of retained austenite is less than 3%, a total area fraction of bainitic ferrite and ferrite is less than 5%, and a 20° or greater grain boundary density in tempered martensite is 1.0 ?m/?m2 or more, satisfying the following Expression ? ( 1 ) ? KAM ? ( S ) / KAM ? ( C ) > 1.

Abstract: A steel sheet, a member, and a method for producing them are disclosed. The steel sheet has a chemical composition containing, in mass %: C: not less than 0.15% and not more than 0.45%; Si: not less than 0.3% and not more than 2.0%; Mn: not less than 1.7% and not more than 4.0%; P: not more than 0.10%; S: not more than 0.01%; sol. Al: not more than 0.50%; N: not more than 0.010%; and B: not less than 0.0008% and not more than 0.0100%, with the balance being Fe and incidental impurities, wherein the steel sheet has a steel microstructure where the area ratio of martensite to the entire microstructure is not less than 85% and less than 95%, and the area ratio of retained austenite to the entire microstructure is not less than 5% and not more than 15%, and wherein the number density A of precipitates having an equivalent circular diameter of 500 nm or more satisfies the formula: A (number/mm2)?8.5×105×[B].

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 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: 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: 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.