Abstract: A hot-rolled steel sheet consists of, in mass %, C: 0.03-0.2%, Mn: 0.1-3.0%, P: 0.10% or less, S: 0.03% or less, Al+Si: 0.2-3.0%, N: more than 0% to 0.01%, O: more than 0% to 0.01%, and balance: iron and impurities. A microstructure contains ferrite and hard phases of martensite and/or austenite in an amount of, in area fraction, 3% to less than 20%. Hard phases with an aspect ratio of 3 or more account for 60% or more of the hard phases present in a sheet-thickness central portion. A length in a rolling direction of the hard phases is less than 20 ?m. An average aspect ratio of ferrite grains is less than 5. The sum of X-ray random intensity ratios of <011> and <111> orientation from the rolling direction is 3.5 or more, and an X-ray random intensity ratio of <001> orientation from the rolling direction is 1.0 or less.

Abstract: A hot-rolled steel sheet includes a predetermined chemical composition, and a structure which include, by area ratio, ferrite and bainite in a range of 80% to 98% in total, and martensite in a range of 2% to 10%, in which in the structure, in a case where a boundary having an orientation difference of equal to or greater than 15° is defined as a grain boundary, and an area which is surrounded by the grain boundary, and has an equivalent circle diameter of equal to or greater than 0.3 ?m is defined as a grain, the ratio of the grains having an intragranular orientation difference in a range of 5° to 14° is, by area ratio, in a range of 10% to 60%.

Abstract: A hot-rolled steel sheet includes a predetermined chemical composition, and a structure which includes, by area ratio, a ferrite in a range of 5% to 60% and a bainite in a range of 30% to 95%, in which in the structure, in a case where a boundary having an orientation difference of equal to or greater than 15° is defined as a grain boundary, and an area which is surrounded by the grain boundary and has an equivalent circle diameter of equal to or greater than 0.3 ?m is defined as a grain, the ratio of the grains having an intragranular orientation difference in a range of 5° to 14° is, by area ratio, in a range of 20% to 100%.

Abstract: A hot-rolled steel sheet includes a chemical composition represented by, in mass %, C: 0.010% to 0.100%, Si: 0.30% or less, Cr: 0.05% to 1.00%, Nb: 0.003% to 0.050%, Ti: 0.003% to 0.200% and others, wherein a proportion of grains having an intragranular misorientation of 5° to 14° in all grains is 20% or more by area ratio, the grain being defined as an area which is surrounded by a boundary having a misorientation of 15° or more and has a circle-equivalent diameter of 0.3 ?m or more.

Abstract: A hot-rolled steel sheet includes a predetermined chemical composition, and a structure which includes, by area ratio, ferrite and bainite in a range of 75% to 95% in total, and martensite in a range of 5% to 20%, in which in the structure, in a case where a boundary having an orientation difference of equal to or greater than 15° is set as a grain boundary, and an area which is surrounded by the grain boundary, and has an equivalent circle diameter of equal to or greater than 0.3 ?m is defined as a grain, the ratio of the grains having an intragranular orientation difference in a range of 5° to 14° is, by area ratio, in a range of 10% to 60%.

Abstract: A dual phase steel sheet including: in mass %, C: 0.01 to 0.1%; Mn: 0.2 to 3%; Al: 0.04 to 1.5%; Ti: 0.015 to 0.2%; P: 0.01% or less; S: 0.005% or less; N: 0.01% or less, in which [Ti]?48/14×[N]?48/32×[S]?0% is satisfied and when Ex.C (%)=[C]?12/48×{[Ti]+48/93×[Nb]?48/14×[N]?48/32×[S]} is set, 0.001?Ex.C (%)/fsd (%)?0.01 is satisfied, and a balance being composed of Fe and impurities, in which at the position of ¼ thickness of a sheet thickness, a microstructure is a dual phase with its main phase composed of polygonal ferrite precipitation-strengthened by carbide of Ti and its second phase composed of 1 to 10% in area fraction (fsd (%)) of low-temperature transformation products dispersed plurally, and an average crystal diameter of the low-temperature transformation product is 3 to 15 ?m and an average value of a distance of closest approach between the low-temperature transformation products is 10 to 20 ?m.

Abstract: A hot-rolled steel sheet includes a specific chemical composition, and includes a microstructure represented by, in vol %: retained austenite: 2% to 30%; ferrite: 20% to 85%; bainite: 10% to 60%; pearlite: 5% or less; and martensite: 10% or less. A proportion of grains having an intragranular misorientation of 5° to 14° in all grains is 5% to 50% by area ratio, the grain being defined as an area which is surrounded by a boundary having a misorientation of 15° or more and has a circle-equivalent diameter of 0.3 ?m or more.

Abstract: In a hot-rolled steel sheet, an average pole density of an orientation group of {100}<011> to {223}<110>, which is represented by an arithmetic average of pole density of each orientation of {100}<011>, {116}<110>, {114}<110>, {112}<110>, and {223}<110> in a center portion of a sheet thickness which is a range of the sheet thickness of ? to ? from a surface of the steel sheet, is 1.0 or more and 4.0 or less, the pole density of a crystal orientation of {332}<113> is 1.0 or more and 4.8 or less, an average grain size in a center in the sheet thickness is 10 ?m or less, and a microstructure includes, by a structural fraction, pearlite more than 6% and ferrite in the balance.

Abstract: In a hot-rolled steel sheet, an average pole density of an orientation group {100}<011> to {223}<110>, which is represented by an arithmetic mean of pole densities of orientations {100}<011>, {116}<110>, {114}<110>, {112}<110>, and {223}<110> is 1.0 to 4.0 and a pole density of a crystal orientation {332}<113> is 1.0 to 4.8, in a thickness center portion which is a thickness range of ? to ? from the surface of the steel sheet; an average grain size in the thickness center portion is less than or equal to 10 ?m and a grain size of cementite precipitating in a grain boundary of the steel sheet is less than or equal to 2 ?m; and an average grain size of precipitates containing TiC in grains is less than or equal to 3 nm and a number density per unit volume is greater than or equal to 1×1016 grains/cm3.

Abstract: A hot-rolled steel sheet according to the present invention has a chemical composition comprising, in mass %, C: 0.03 to 0.2%, Mn: 0.1 to 3.0%, P: 0.10% or less, S: 0.03% or less, Al+Si: 0.2 to 3.0%, N: more than 0% and equal to or less than 0.01%, O: more than 0% and equal to or less than 0.01%, and the balance: iron and impurities. A microstructure of the hot-rolled steel sheet contains bainite as the main constituent, and contains hard phases constituted by martensite and/or austenite in an amount of, in area fraction, equal to or more than 3% and less than 20% where 60% or more of the hard phase present in a sheet-thickness central portion have an aspect ratio of 3 or more, the hard phases present in the sheet-thickness central portion have a length in a rolling direction of less than 20 ?m, and the sum of X-ray random intensity ratios of <011> orientation and <111> orientation as viewed from the rolling direction is 3.

Abstract: [Object] To provide a hot-rolled steel sheet having excellent fatigue characteristics and workability in the rolling direction. [Solution] A hot-rolled steel sheet according to the present invention has a chemical composition consisting of, in mass %, C: 0.03 to 0.2%, Mn: 0.1 to 3.0%, P: 0.10% or less, S: 0.03% or less, Al+Si: 0.2 to 3.0%, N: more than 0% and equal to or less than 0.01%, O: more than 0% and equal to or less than 0.01%, and the balance: iron and impurities.

Abstract: The present invention provides a bainite-containing-type high-strength hot-rolled steel sheet. The steel sheet, containing C: greater than 0.07 to 0.2%, Si: 0.001 to 2.5%, Mn: 0.01 to 4%, P: 0.15% or less, S: 0.03% or less, N: 0.01% or less, Al: 0.001 to 2% and a balance being composed of Fe and impurities, has an average value of pole densities of the {100}<011> to {223}<110> orientation group at a sheet thickness center portion being a range of ? to ? in sheet thickness from the surface of the steel sheet is 4.0 or less, and a pole density of the {332}<113> crystal orientation is 4.8 or less, an average crystal grain diameter is 10 ?m or less and vTrs is ?20° C. or lower, and a microstructure is composed of 35% or less in a structural fraction of pro-eutectoid ferrite and a balance of a low-temperature transformation generating phase.

Abstract: The present invention provides a bainite-containing-type high-strength hot-rolled steel sheet. The steel sheet, containing C: greater than 0.07 to 0.2%, Si: 0.001 to 2.5%, Mn: 0.01 to 4%, P: 0.15% or less, S: 0.03% or less, N: 0.01% or less, Al: 0.001 to 2% and a balance being composed of Fe and impurities, has an average value of pole densities of the {100}<011> to {223}<110> orientation group at a sheet thickness center portion being a range of ? to ? in sheet thickness from the surface of the steel sheet is 4.0 or less, and a pole density of the {332}<113> crystal orientation is 4.8 or less, an average crystal grain diameter is 10 ?m or less and vTrs is ?20° C. or lower, and a microstructure is composed of 35% or less in a structural fraction of pro-eutectoid ferrite and a balance of a low-temperature transformation generating phase.

Abstract: In a hot-rolled steel sheet, an average pole density of an orientation group of {100}<011> to {223}<110>, which is represented by an arithmetic average of pole density of each orientation of {100}<011>, {116}<110>, {114}<110>, {112}<110>, and {223}<110> in a center portion of a sheet thickness which is a range of the sheet thickness of ? to ? from a surface of the steel sheet, is 1.0 or more and 4.0 or less, the pole density of a crystal orientation of {332}<113> is 1.0 or more and 4.8 or less, an average grain size in a center in the sheet thickness is 10 ?m or less, and a microstructure includes, by a structural fraction, pearlite more than 6% and ferrite in the balance.

Abstract: A high-strength cold-rolled steel sheet having excellent stretch flangeability and precision punchability containing predetermined components and a balance being composed of iron and inevitable impurities, in which in a range of ? to ? in sheet thickness from the surface of the steel sheet, an average value of pole densities of the {100}<011> to {223}<110> orientation group represented by respective crystal orientations of {100}<011>, {116}<110>, {114}<110>, {113}<110>, {112}<110>, {335}<110>, and {223}<110> is 6.5 or less, and a pole density of the {332}<113> crystal orientation is 5.0 or less, and a metal structure contains, in terms of an area ratio, greater than 5% of pearlite, the sum of bainite and martensite limited to less than 5%, and a balance composed of ferrite.

Abstract: In a hot-rolled steel sheet, an average pole density of an orientation group of {100}<011> to {223}<110>, which is represented by an arithmetic average of pole density of each orientation of {100}<011>, {116}<110>, {114}<110>, {112}<110>, and {223}<110> in a center portion of a sheet thickness which is a range of the sheet thickness of ? to ? from a surface of the steel sheet, is 1.0 or more and 4.0 or less, the pole density of a crystal orientation of {332}<113> is 1.0 or more and 4.8 or less, an average grain size in a center in the sheet thickness is 10 ?m or less, and a microstructure includes, by a structural fraction, pearlite more than 6% and ferrite in the balance.

Abstract: There is provided a hot-rolled steel sheet in which a composition contains: in mass %, C: 0.01% to 0.2%; Si: 2.5% or less; Mn: 4.0% or less; P: 0.10% or less; S: 0.03% or less; Al: 0.001% to 2.0%; N: 0.01% or less; O: 0.01% or less; Ti: 0.01 to 0.30%; and the balance being composed of iron and impurities and a structure is composed of by volume fraction, 90% or more of tempered martensite with an average aspect ratio of 2 or less, or 90% or more in total of both tempered martensite and lower bainite.

Abstract: A hot-rolled steel sheet has a composition containing: in mass %, C: 0.01 to 0.2%; Si: 2.5% or less; Mn: 4.0% or less; P: 0.10% or less; S: 0.03% or less; Al: 0.001 to 2.0%; N: 0.01% or less; and O: 0.01% or less, and one kind or a total of two kinds of Ti and Nb for 0.01 to 0.30%. An average effective crystal grain diameter at a sheet thickness ¼ part is 10 ?m or less, and an average effective crystal grain diameter at a part of a range of 50 ?m from a surface is 6 ?m or less. A structure of the steel sheet is tempered martensite or lower bainite, and a volume fraction thereof is 90% or more as a total.

Abstract: Provided is a high-strength hot-rolled steel sheet consisting of, in mass %, C: 0.01% to 0.2%, Si: 0% to 2.5%, Mn: 0% to 4.0%, Al: 0% to 2.0%, N: 0% to 0.01%, Cu: 0% to 2.0%, Ni: 0% to 2.0%, Mo: 0% to 1.0%, V: 0% to 0.3%, Cr: 0% to 2.0%, Mg: 0% to 0.01%, Ca: 0% to 0.01%, REM: 0% to 0.1%, B: 0% to 0.01%, P: less than or equal to 0.10%, S: less than or equal to 0.03%, O: less than or equal to 0.01%, one or both of Ti and Nb: 0.01% to 0.30% in total, and the balance being Fe and inevitable impurities. The steel sheet has a structure in which a total volume fraction of tempered martensite or lower bainite is 90% or more, a dislocation density thereof is greater than or equal to 5×1013 (1/m2) and less than or equal to 1×1016 (1/m2) and 1×106 (numbers/mm2) or more iron-based carbides are included therein.

Abstract: A dual phase steel sheet including: in mass %, C: 0.01 to 0.1%; Mn: 0.2 to 3%; Al: 0.04 to 1.5%; Ti: 0.015 to 0.2%; P: 0.01% or less; S: 0.005% or less; N: 0.01% or less, in which [Ti]?48/14×[N]?48/32×[S]?0% is satisfied and when Ex.C (%)=[C]?12/48×{[Ti]+48/93×[Nb]?48/14×[N]?48/32×[S]} is set, 0.001?Ex.C (%)/fsd (%)?0.01 is satisfied, and a balance being composed of Fe and impurities, in which at the position of ¼ thickness of a sheet thickness, a microstructure is a dual phase with its main phase composed of polygonal ferrite precipitation-strengthened by carbide of Ti and its second phase composed of 1 to 10% in area fraction (fsd (%)) of low-temperature transformation products dispersed plurally, and an average crystal diameter of the low-temperature transformation product is 3 to 15 ?m and an average value of a distance of closest approach between the low-temperature transformation products is 10 to 20 ?m.