Abstract: A galvanized steel sheet according to the present invention includes a steel sheet and a galvanizing layer which is formed on a surface of the steel sheet. The steel sheet includes as a chemical component, by mass %, C: more than 0.100% to 0.500%, Si: 0.0001% to less than 0.20%, Mn: more than 0.20% to 3.00%, Al: 3.0% to 10.0%, N: 0.0030% to 0.0100%, Ti: more than 0.100% to 1.000%, P: 0.00001% to 0.0200%, S: 0.00001% to 0.0100% and a remainder including Fe and impurities. The galvanizing layer includes as a chemical composition, by mass %, Fe: 0.01% to 15% and a remainder including Zn and impurities. The galvanized steel sheet has a specific gravity of 5.5 to less than 7.5.

Abstract: A hot-rolled steel sheet has an average value of the X-ray random intensity ratio of a {100} <011> to {223} <110> orientation group at least in a sheet thickness central portion that is in a sheet thickness range of ? to ? from a steel sheet surface of 1.0 to 6.0, an X-ray random intensity ratio of a {332} <113> crystal orientation of 1.0 to 5.0, rC which is an r value in a direction perpendicular to a rolling direction of 0.70 to 1.10, and r30 which is an r value in a direction that forms an angle of 30° with respect to the rolling direction of 0.70 to 1.10.

Abstract: In a hot-rolled sheet, an average value of pole densities 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> in a thickness center portion of a thickness range of ? to ? from a surface of the steel sheet, is 1.0 to 6.5 and a pole density of a crystal orientation {332}<113> is 1.0 to 5.0; and a Lankford value rC in a direction perpendicular to a rolling direction is 0.70 to 1.10 and a Lankford value r30 in a direction that forms 30° with respect to the rolling direction is 0.70 to 1.10.

Abstract: A steel sheet including, by mass %, C: more than 0.100% and 0.500% or less, Si: 0.0001% or more and less than 0.20%, Mn: more than 0.20% and 0.50% or less, Al: 3.0% or more and 10.0% or less, N: 0.0030% or more and 0.0100% or less, Ti: more than 0.100% and 1.000% or less, P: 0.00001% or more and 0.0200% or less, S: 0.00001% or more and 0.0100% or less, and a remainder including Fe and impurities, in which a sum of a C content and a Ti content satisfies 0.200<C+Ti?1.500 by mass %, a product of an Al content and an Si content satisfies Al×Si?0.8 by mass %, and a specific gravity is 5.5 to less than 7.5.

Abstract: Provided is a galvanized steel sheet having a tensile strength of 770 MPa or more including a steel sheet portion, and a plated layer formed on the surface of the steel sheet portion, in which the plated layer is a galvanized plated layer or an galvannealed plated layer, the steel sheet portion has a soft layer that directly adjoins the interface with the plated layer and an inside layer that is other than the soft layer, the thickness D of soft layer is 0.001% to 5% of thickness t of the steel sheet portion, and, when the hardness of the soft layer measured by nano-indentation method is indicated by H1, and the representative hardness of the steel sheet portion measured by the nano-indentation method is indicated by Ha in cross section that goes along the thickness direction of the steel sheet portion, H1 is 5% to 75% of Ha.

Abstract: A high-strength cold-rolled steel sheet includes, by mass %, C: 0.10% to 0.40%, Mn: 0.5% to 4.0%, Si: 0.005% to 2.5%, Al: 0.005% to 2.5%, Cr: 0% to 1.0%, and a balance of iron and inevitable impurities, in which an amount of P is limited to 0.05% or less, an amount of S is limited to 0.02% or less, an amount of N is limited to 0.006% or less, the microstructure includes 2% to 30% of retained austenite by area percentage, martensite is limited to 20% or less by area percentage in the microstructure, an average particle size of cementite is 0.01 ?m to 1 ?m, and 30% to 100% of the cementite has an aspect ratio of 1 to 3.

Abstract: There are provided a high-strength hot-rolled steel sheet securing low-temperature toughness and having excellent stretch flangeability by controlling a structural fraction and a hardness difference among structures, and a manufacturing method thereof. A hot-rolled steel sheet contains: C: 0.01 to 0.2%; Si: 0.001 to 2.5% or less; Mn: 0.10 to 4.0% or less; P: 0.10% or less; S: less than 0.03%; Al: 0.001 to 2.0%; N: less than 0.01%; Ti: (0.005+48/14[N]+48/32[S]) % or more and 0.3% or less; Nb: 0 to 0.06%; Cu: 0 to 1.2%; Ni: 0 to 0.6%; Mo: 0 to 1%; V: 0 to 0.2%; Cr: 0 to 2%; Mg: 0 to 0.01%; Ca: 0 to 0.01%; REM: 0 to 0.1%; and B: 0 to 0.002%, and has: an texture in which, at a central portion of a sheet thickness located between ? to ? thickness positions of the sheet thickness from a surface of the steel sheet, an average value of X-ray random intensity ratios of a group of {100}<011> to {223}<110> orientations of a sheet plane is 6.

Abstract: A high-strength cold-rolled steel sheet includes, as a component composition, by mass %: C: 0.075% to 0.300%; Si: 0.30% to 2.50%; Mn: 1.30% to 3.50%; P: 0.001% to 0.050%; S: 0.0001% to 0.0100%; Al: 0.001% to 1.500%; and N: 0.0001% to 0.0100%, in which a surface microstructure contains residual austenite of 3% to 10% and ferrite of 90% or less by volume fraction, an inner microstructure at a depth of t/4 from the surface assuming that a sheet thickness is t contains residual austenite of 3% to 20% by volume fraction, a ratio Hvs/Hvb between a surface hardness Hvs of the steel sheet surface and a hardness Hvb at a depth of ¼ of the thickness is more than 0.75 to 0.90, and a maximum tensile strength is 700 MPa or more.

Abstract: The high-strength steel sheet includes, by mass %: C: 0.01% to 0.10%; Si: 0.15% or less; Mn: 0.80% to 1.80%; P: 0.10% or less; S: 0.015% or less; Al: 0.10% to 0.80%; Cr: 0.01% to 1.50%; N: 0.0100% or less; and a balance consisting of iron and inevitable impurities, in which a metallic structure is composed of ferrite and a hard second phase, the area fraction of the ferrite is 80% or more, the area fraction of the hard second phase is 1% to 20%, the fraction of unrecrystallized ferrite in the ferrite is less than 10%, the ferrite grain sizes are 5 ?m to 20 ?m, and the fraction of the ferrite crystal grains having an aspect ratio of 1.2 or less in the entire ferrite crystal grains is 60% or more.

Abstract: This high strength hot-rolled steel sheet includes: in terms of percent by mass, C: 0.05 to 0.12%; Si: 0.8 to 1.2%; Mn: 1.6 to 2.2%; Al: 0.30 to 0.6%; P: 0.05% or less; S: 0.005% or less; and N: 0.01% or less, with the remainder being Fe and unavoidable impurities, wherein a microstructure includes specific ranges (in area %) of ferrite phases as well as martensite phases, and a maximum concentration of Al detected by a glow discharge emission spectroscopic analysis is in a range of 0.75 mass % or less in a region from a surface of the steel sheet to a thickness of 500 nm after being acid-pickled.

Abstract: Provided is a high-strength hot-dip galvanized steel sheet having excellent plating adhesion, formability, and hole expandability with an ultimate tensile strength of 980 MPa or more, the hot-dip galvanized steel sheet comprising a hot-dip galvanized layer formed on a surface of a base steel sheet. The base steel sheet contains, by mass %, C: 0.05% to 0.4%; Si: 0.01% to 3.0%; Mn: 0.1% to 3.0%; Al: 0.01 to 2.0%; in which Si+Al>0.5%, P: limited to 0.04% or less; S: limited to 0.05% or less; N: limited to 0.01% or less; and a balance including Fe and inevitable impurities, a microstructure of the base steel sheet contains 40% or more by total volume fraction of martensite and bainite, 8% or more by volume fraction of residual austenite, and a balance of the microstructure being ferrite or ferrite and 10% or less by volume fraction of pearlite.

Abstract: This high-strength steel sheet includes: in terms of percent by mass, 0.03 to 0.10% of C; 0.01 to 1.5% of Si; 1.0 to 2.5% of Mn; 0.1% or less of P; 0.02% or less of S; 0.01 to 1.2% of Al; 0.06 to 0.15% of Ti; and 0.01% or less of N; and contains as the balance, iron and inevitable impurities, wherein a tensile strength is in a range of 590 MPa or more, and a ratio between the tensile strength and a yield strength is in a range of 0.80 or more, a microstructure includes bainite at an area ratio of 40% or more and the balance being either one or both of ferrite and martensite, a density of Ti(C,N) precipitates having sizes of 10 nm or smaller is in a range of 1010 precipitates/mm3 or more, and a ratio (Hvs/Hvc) of a hardness (Hvs) at a depth of 20 ?m from a surface to a hardness (Hvc) at a center of a sheet thickness is in a range of 0.85 or more.

Abstract: This high-strength steel sheet includes: in terms of percent by mass, 0.03 to 0.10% of C; 0.01 to 1.5% of Si; 1.0 to 2.5% of Mn; 0.1% or less of P; 0.02% or less of S; 0.01 to 1.2% of Al; 0.06 to 0.15% of Ti; and 0.01% or less of N; and contains as the balance, iron and inevitable impurities, wherein a tensile strength is in a range of 590 MPa or more, and a ratio between the tensile strength and a yield strength is in a range of 0.80 or more, a microstructure includes bainite at an area ratio of 40% or more and the balance being either one or both of ferrite and martensite, a density of Ti(C,N) precipitates having sizes of 10 nm or smaller is in a range of 1010 precipitates/mm3 or more, and a ratio (Hvs/Hvc) of a hardness (Hvs) at a depth of 10 ?m from a surface to a hardness (Hvc) at a center of a sheet thickness is in a range of 0.85 or more.

Abstract: This high strength hot-rolled steel sheet includes: in terms of percent by mass, C: 0.05 to 0.12%; Si: 0.8 to 1.2%; Mn: 1.6 to 2.2%; Al: 0.30 to 0.6%; P: 0.05% or less; S: 0.005% or less; and N: 0.01% or less, with the remainder being Fe and unavoidable impurities, wherein a microstructure includes specific ranges (in area %) of ferrite phases as well as martensite phases, and a maximum concentration of Al detected by a glow discharge emission spectroscopic analysis is in a range of 0.75 mass % or less in a region from a surface of the steel sheet to a thickness of 500 nm after being acid-pickled.

Abstract: Provided is a high-strength hot-dip galvanized steel sheet having small material anisotropy and excellent formability with an ultimate tensile strength of 980 MPa or more. The hot-dip galvanized steel sheet includes a hot-dip galvanized layer formed on a surface of a base steel plate. The base steel plate contains, by mass %, C: 0.1 to less than 0.40%, Si: 0.5 to 3.0%, Mn: 1.5 to 3.0%, O: limited to 0.006% or less, P: limited to 0.04% or less, S: limited to 0.01% or less, Al: limited to 2.0% or less, N: limited to 0.01% or less, and a balance including Fe and inevitable impurities. A microstructure of the base steel sheet contains ferrite of 40% or more, residual austenite of 8 to less than 60%, by volume fraction, and a balance being bainite or martensite. In a sheet thickness range of ? to ? from the surface of the base steel sheet, a pole density of specific crystal orientation is within a predetermined range.

Abstract: A hot-dip galvanized steel sheet includes: a steel sheet; and a plated layer on a surface of the steel sheet, a microstructure contains, by volume fraction, equal to or more than 20% and equal to or less than 99% in total of one or two of martensite and bainite, a residual structure contains one or two of ferrite, residual austenite of less than 8% by volume fraction, and pearlite of equal to or less than 10% by volume fraction, tensile strength is equal to or greater than 980 MPa, the plated layer is a hot-dip galvanized layer which contains oxides including one or two or more of Si, Mn, and Al, contains equal to or less than 15 mass % of Fe, and a remainder including Zn, Al, and unavoidable impurities, and when a cross section including the steel sheet and the hot-dip galvanized layer is seen in a sheet thickness direction, a projected area ratio is equal to or more than 10% and equal to or less than 90%.

Abstract: A galvanized steel sheet includes a steel sheet and a plating layer on the surface of the steel sheet, in which the steel sheet includes, as a steel chemical composition, by mass %, C: 0.05 to 0.40%, Si: 0.5 to 3.0% and Mn: 1.5 to 3.0%, a microstructure of the steel sheet includes ferrite, bainite, by volume fraction, 30% or more of a tempered martensite, and 8% or more of an austenite, and tensile strength of the steel sheet is 980 MPa or more, and the plating layer includes an oxide including at least one chemical element selected from Si, Mn and Al, and when seen at a cross section including the steel sheet and the plating layer in a plate thickness direction, a projection area fraction of the oxide is 10% or more.

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: This high-strength hot-rolled steel sheet having excellent local deformability contains, in mass %, C: 0.07% to 0.20%; Si: 0.001% to 2.5%; Mn: 0.01% to 4.0%; P: 0.001% to 0.15%; S: 0.0005% to 0.03%; Al: 0.001% to 2.0%; N: 0.0005% to 0.01%; and O: 0.0005% to 0.01%; and a balance being composed of iron and inevitable impurities, in which an area ratio of bainite in a metal structure is 95% or more, at a sheet thickness center portion being a range of 5/8 to 3/8 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 is 4.0 or less, and a pole density of the {332}<113> crystal orientation is 5.0 or less, and a mean volume diameter of crystal grains in the metal structure is 10 ?m or less.

Abstract: A hot-rolled steel sheet satisfies that average pole density of orientation group of {100}<011> to {223}<110> is 1.0 to 5.0 and pole density of crystal orientation {332}<113> is 1.0 to 4.0. Moreover, the hot-rolled steel sheet includes, as a metallographic structure, by area %, ferrite and bainite of 30% to 99% in total and martensite of 1% to 70%. Moreover, the hot-rolled steel sheet satisfies following Expressions 1 and 2 when area fraction of the martensite is defined as fM in unit of area %, average size of the martensite is defined as dia in unit of ?m, average distance between the martensite is defined as dis in unit of ?m, and tensile strength of the steel sheet is defined as TS in unit of MPa.