Abstract: This zinc-nickel composite plating bath contains a zinc source, a nickel source, silicon dioxide particles and an ammonium-based dispersant in such ranges that enable the achievement of a zinc-nickel composite plating film wherein the codeposition amount of nickel is 10-16 wt % and the codeposition amount of the silicon dioxide particles is 7 vol % or more. Meanwhile, the pH of this zinc-nickel composite plating bath is 5.6 to 6.8.

Abstract: A high-strength steel sheet exhibiting excellent ductility and stretch-flangeability, and a method for manufacturing such a high-strength steel sheet. The high-strength steel sheet has a chemical composition including specific proportions of components in which C/Mn is 0.08 to 0.20, the balance being iron and inevitable impurities, and includes microstructures including, in terms of area fraction relative to all the microstructures, 40% to 70% total of ferrite and bainitic ferrite, 5% to 35% martensite and 5% to 30% retained austenite. The proportion of martensite (including retained austenite) adjacent to bainitic ferrite is not less than 60% of all martensite (including retained austenite). The proportion of 4.0 GPa and smaller differences in microhardness measured at 0.5 ?m intervals is not less than 70%. The proportion of microstructures with 8.0 GPa or smaller microhardness is not less than 85% of all the microstructures.

Abstract: A method of laser spot welding a workpiece stack-up that includes at least two overlapping steel workpieces, at least one of which includes a surface coating, is disclosed. The method includes directing a laser beam at the top surface of the workpiece stack-up to create a molten steel weld pool that penetrates into the stack-up. The molten steel weld pool is then grown to penetrate further into the stack-up by increasing an irradiance of the laser beam while reducing the projected sectional area of the laser beam at a plane of the top surface of the workpiece stack-up. Increasing the irradiance of the laser beam may be accomplished by moving a focal point of the laser beam closer to the top surface or by reducing an angle of incidence of the laser beam so as to reduce the eccentricity of the projected sectional area of the laser beam.

Abstract: A high-strength hot-dip coated hot-rolled steel sheet excellent in terms of surface appearance quality and coating adhesiveness and a method for manufacturing. The method includes performing hot rolling followed by pickling on steel to form a pickled steel sheet, the steel having a chemical composition containing, by mass %, C: 0.02% or more and 0.30% or less, Si: 0.01% or more and 1.0% or less, Mn: 0.3% or more and 2.5% or less, P: 0.08% or less, S: 0.02% or less, Al: 0.001% or more and 0.20% or less, and Fe and inevitable impurities. The method further includes performing rolling with a rolling reduction ratio of 1% or more and 10% or less, and a hot-dip coating treatment. The obtained steel sheet has an arithmetic average roughness Ra of 2.0 ?m or less on the surface of the steel sheet, and a tensile strength of 590 MPa or more.

Abstract: A steel sheet has a microstructure that contains ferrite in an area ratio of 20% or more, martensite in an area ratio of 5% or more, and tempered martensite in an area ratio of 5% or more. The ferrite has a mean grain size of 20.0 ?m or less. An inverse intensity ratio of ?-fiber to ?-fiber in the ferrite is 1.00 or more and an inverse intensity ratio of ?-fiber to ?-fiber in the martensite and the tempered martensite is 1.00 or more.

Abstract: Provided is a method of manufacturing a hot-dip galvanized steel sheet. According to an aspect of the present invention, the method may include preparing a base steel sheet, forming a iron (Fe)-plated layer on the prepared base steel sheet, oxidation heating the steel sheet having the Fe-plated layer formed thereon at a temperature ranging from 600° C. to 800° C., maintaining the heated steel sheet at a temperature ranging from 750° C. to 900° C. for 5 seconds or more in a reducing atmosphere with a dew point of between ?30° C. to 5° C. including 20 ppm or less of oxygen, 1 vol % to 20 vol % of H2, and N2 as well as unavoidable gases as a remainder, cooling the maintained steel sheet, and plating the cooled steel sheet by dipping in a hot-dip galvanizing bath.

Abstract: Stainless steel sheets including a Ni and O-containing coating on the surface that has excellent weld penetration characteristics and excellent crevice corrosion resistance, and a method for producing such stainless steel sheets. A stainless steel sheet includes a Ni and O-containing coating on a surface of the stainless steel sheet. The Ni and O-containing coating has a coating weight of greater than or equal to 0.1 g/m2 and less than or equal to 20 g/m2. The Ni and O-containing coating has a composition including, in at. %, Ni: greater than or equal to 25% and less than or equal to 60%, and O: greater than or equal to 40% and less than or equal to 70%.

Abstract: Provided is an ultra-high strength steel sheet having excellent phosphatability and bendability. The ultra-high strength steel sheet includes, by weight percentage (wt %), carbon (C): 0.08% to 0.2%, silicon (Si): 0.05% to 1.3%, manganese (Mn): 2.0% to 3.0%, phosphorus (P): 0.001% to 0.10%, sulfur (S): 0.010% or less, aluminum (Al): 0.01% to 0.1%, chromium (Cr): 0.3% to 1.2%, boron (B): 0.0010% to 0.0030%, titanium (Ti): 0.01% to 0.05%, nitrogen (N): 0.001% to 0.01%, a remainder of iron (Fe) and other inevitable impurities, satisfying: 3.4?Ti/N?10, 1.0?Mn/(Si+Cr), and 0.7?Mn*/(Si*+Cr*)?Mn/(Si+Cr), where Ti, N, Mn, Si and Cr refer to a weight percentage (wt %), and Mn*, Si* and Cr* refer to an average of values obtained by GDS component analysis from a surface to a 0.1 ?m position in a thickness direction.

Abstract: A cold-rolled ultra-high strength, multi-phase structured steel is disclosed with improved stamping and forming performance during manufacturing processes, while possessing one or more of the following properties: excellent castability and rollability, excellent galvanizability and/or coatability, excellent formability, excellent fracture resistance, excellent stretch formability and stretch flangeability, excellent dent resistance, excellent durability, excellent impact performance and structural performance, excellent intrusion and crash resistance, and excellent weldability, without the purposeful addition of boron.

Abstract: There is provided a hot-dip galvanized steel sheet with a microstructure in a ? thickness to ? thickness range whose middle is a ¼ thickness from a surface of a base steel sheet, the microstructure contains ferrite phase is 50% or more and 97% or less by volume fraction, and a predetermined phase wherein at an interface between a hot-dip galvanizing layer and the base steel sheet, a Fe—Al alloy layer has an average thickness of 0.1 ?m to 2.0 ?m, and a difference between a maximum thickness and a minimum thickness in a steel sheet width direction is within 0.5 ?m, and in a fine-grain layer directly brought into contact with the Fe—Al alloy layer, the fine-grain has a difference between a maximum thickness and a minimum thickness of the fine-grain layer in the steel sheet width direction is within 2.0 ?m.

Abstract: A steel sheet has a microstructure that contains ferrite in an area ratio of 20% or more, martensite in an area ratio of 5% or more, and tempered martensite in an area ratio of 5% or more. The ferrite has a mean grain size of 20.0 ?m or less. An inverse intensity ratio of ?-fiber to ?-fiber in the ferrite is 1.00 or more and an inverse intensity ratio of ?-fiber to ?-fiber in the martensite and the tempered martensite is 1.00 or more.

Abstract: Provided herein is a plated steel having high strength with excellent elongation, excellent hole expansibility, and excellent material uniformity, and a method for producing such a plated steel. The steel sheet provided herein has a specific composition, and a steel structure that contains ferrite as a primary phase, and 2 to 12% of perlite, and 3% or less of martensite by volume, and in which the remainder is a low-temperature occurring phase. The ferrite has an average crystal grain diameter of 25 ?m or less. The perlite has an average crystal grain diameter of 5 ?m or less. The martensite has an average crystal grain diameter of 1.5 ?m or less. The perlite has a mean free path of 5.5 ?m or more. The steel sheet has a tensile strength of 440 MPa or more.

Abstract: A steel sheet having low yield ratio, tensile strength of 780 MPa or more, and good bending fatigue properties. The steel sheet includes a specific chemical composition and a steel microstructure having an area percentage of a ferrite phase of 20% or more and 80% or less and an area percentage of a martensite phase of 20% or more and 80% or less, the area percentage being determined by microstructure observation, in which a surface layer portion of the steel sheet has an average ferrite grain size of 5.0 ?m or less and an inclusion density of 200 particles/mm?2 or less, and in which the steel sheet has a surface hardness of 95% or more when the steel sheet has a hardness of 100% at a position ½t, where t represents the thickness of the steel sheet, away from a surface of the steel sheet in the thickness direction.

Abstract: A steel sheet according to an aspect of the present invention has a chemical composition within a predetermined range; in which a metallographic structure at a thickness ¼ portion includes, by unit area %, ferrite: 10% or more and less than 50%, granular bainite: 5% or more and less than 50%, and martensite: 20% or more and less than 60%; in the metallographic structure at the thickness ¼ portion, a total of upper bainite, lower bainite, residual austenite, and pearlite is 0% or more and less than 15% by unit area %; at the thickness ¼ portion, a product of an area ratio Vm of the martensite and an average hardness Hv of the martensite is 12,000 to 34,000; and a tensile strength is 980 MPa or higher.

Abstract: A steel sheet for a drawn can has a predetermined chemical composition and has a ferrite single-phase structure with a crystal grain size number of 11.0 or more, the sheet thickness is 0.15 to 0.50 mm, in an L direction of the steel sheet after an ageing treatment at 100° C. for one hour, an yield strength YP is 220 to 290 MPa, a tensile strength TS is 330 to 390 MPa, a total elongation EL is 32% or more, an yield point elongation YP-EL is 0%, an average plastic strain ratio rm is more than 1.35, and an in-plane anisotropy ?r is ?0.30 to +0.15.

Abstract: A method for producing a high strength coated steel sheet having an improved ductility and an improved formability, the chemical composition of the steel containing: 0.13%?C?0.22%, 1.9%?Si?2.3%, 2.4%?Mn?3%, Al?0.5%, Ti<0.05%, Nb<0.05%, the remainder being Fe and unavoidable impurities. The sheet is annealed at temperature TA higher than Ac3 but less than 1000° C. for a time of more than 30 s, quenched by cooling to a quenching temperature QT between 200° C. and 280° C. in order to obtain a structure consisting of austenite and at least 50% of martensite, the austenite content being such that the final structure can contain between 3% and 15% of residual austenite and between 85% and 97% of the sum of martensite and bainite, without ferrite, heated up to a partitioning temperature PT between 430° C. and 490° C. and maintained at this temperature for a time Pt between 10 s and 100 s, hot dip coated and cooled to the room temperature.

Abstract: Provided herein is a steel sheet of a specific composition that has a micro structure containing, by volume, 75 to 95% of ferrite, 3 to 15% of martensite, 0.5 to 10% of perlite, 10% or less of unrecrystallized ferrite, and 21.5% or less of a low-temperature occurring phase representing the remainder, and in which the ferrite has an average crystal grain diameter of 6 ?m or less, and the martensite has an average crystal grain diameter of 3 ?m or less, and an average aspect ratio of 4.0 or less, and in which a Nb base precipitate having an average grain diameter of 0.10 ?m or less is contained. The steel sheet has a tensile strength of 590 MPa or more.

Abstract: A high strength steel sheet mainly used as an automotive exterior panel material is provided. In detail, a complex-phase steel sheet having excellent formability and a method of manufacturing the same are provided. A steel sheet may have excellent strength and ductility, and a relatively low yield ratio and an excellent surface quality may be provided.

Abstract: A hot-dip galvanized steel sheet includes a base steel sheet and a hot-dip galvanized layer formed on at least one surface of the base steel sheet, in which the hot-dip galvanized layer includes Fe in a content of more than 0% to 5% or less, Al in a content of more than 0% to 1.0% or less, and columnar grains formed by a ? phase on the surface of the steel sheet, further, 20% or more of the entire interface between the hot-dip galvanized layer and the base steel sheet is coated with the ? phase, and a ratio of an interface formed between ? grains in which coarse oxides are present among ? grains and the base steel sheet with respect to the entire interface between the ? phase and the base steel sheet in the hot-dip galvanized layer is 50% or less, the base steel sheet has predetermined chemical components and a refined layer in direct contact with the interface between the base steel sheet and the hot-dip galvanized layer, an average thickness of the refined layer is 0.1 to 5.

Abstract: A hot-dip galvanized steel sheet includes a base steel sheet and a hot-dip galvanized layer formed on at least one surface of the base steel sheet, in which the hot-dip galvanized layer includes Fe in a content of more than 0% to 5% or less, Al in a content of more than 0% to 1.0% or less, and columnar grains formed by a ? phase on the surface of the steel sheet, further, 20% or more of the entire interface between the hot-dip galvanized layer and the base steel sheet is coated with the ? phase, and a ratio of an interface formed between ? grains in which coarse oxides are present among grains and the base steel sheet with respect to the entire interface between the ? phase and the base steel sheet in the hot-dip galvanized layer is 50% or less, the base steel sheet has predetermined chemical components and a refined layer in direct contact with the interface between the base steel sheet and the hot-dip galvanized layer, an average thickness of the refined layer is 0.1 to 5.

Abstract: A steel sheet according to an aspect of the present invention has predetermined chemical composition, in which a structure at a thickness ¼ portion includes, in terms of volume ratios, tempered martensite: 30% to 70% and one or both of ferrite and bainite: a total of 20% to 70%, in the structure at the thickness ¼ portion, a volume ratio of residual austenite is less than 10%, a volume ratio of fresh martensite is 10% or less, a volume ratio of pearlite is 10% or less, and a total volume ratio of the residual austenite, the fresh martensite, and the pearlite is 15% or less, a number density of iron-based carbides having a major axis of 5 nm or more in the tempered martensite at the thickness ¼ portion is 5×107 particles/mm2 or more, a ratio of the number of ?-type carbides in the number of the iron-based carbides having the major axis of 5 nm or more at the thickness ¼ portion is 20% or more, and a tensile strength is 780 MPa or higher.

Abstract: Provided is a galvannealed steel sheet having high strength and excellent deep drawability, and being further excellent in slab cracking resistance and secondary working embrittlement resistance. A base metal steel sheet of the galvannealed steel sheet has a chemical composition containing, in mass %: C: 0.0080% or less; Si: 0.7% or less; Mn: 1.0 to 2.5%; P: more than 0.030 to 0.048%; S: 0.025% or less; Al: 0.005 to 0.20%; N: 0.010% or less; Ti: 0.005 to 0.040%; Nb: 0.005 to 0.060%; and B: 0.0005 to 0.0030%, with the balance being Fe and impurities, satisfying Formula (1) to (4). A galvannealed layer contains 7 to 15 mass % of Fe. 25×P+4×Si?3.6??(1) B?X1?0.0005??(2) C?(12/93)×Nb?X2??0.

Abstract: The present invention provides a method for MIG brazing an Al alloy to a steel sheet so as to manufacture a lap joint member that excels in bonding strength with respect to the Al alloy. With the MIG brazing method, a bonding target sheet, specifically, an Al sheet or an Al alloy sheet is bonded to a hot dip Zn-based alloy coated steel sheet (1) whose coating layer contains Al in an amount of 1.0% by mass to 22.0% by mass. A target location of MIG brazing is a region between (i) an intersection (C) of one end of an end surface (6) of the bonding target sheet and the hot dip Zn-based alloy coated steel sheet and (ii) the other end (U) of the end surface of the bonding target sheet.

Abstract: A steel sheet according to an aspect of the present invention has predetermined chemical composition, in which a structure at a thickness ¼ portion includes, in terms of volume ratios, tempered martensite: 70% or more and one or both of ferrite and bainite: a total of less than 20%, in the structure at the thickness ¼ portion, a volume ratio of residual austenite is less than 10%, a volume ratio of fresh martensite is 10% or less, a volume ratio of pearlite is 10% or less, and a total volume ratio of the residual austenite, the fresh martensite, and the pearlite is 15% or less, a number density of iron-based carbides having a major axis of 5 nm or more in the tempered martensite at the thickness ¼ portion is 5×107 particles/mm2 or more, a ratio of the number of ?-type carbides in the number of the iron-based carbides having the major axis of 5 nm or more at the thickness ¼ portion is 20% or more, and a tensile strength is 780 MPa or higher.

Abstract: The present invention provides a method for manufacturing a metal sheet. In this method, at least one of the following equations is satisfied: Z d + 18 ? ? ln ? ( Z d ) < 8 ? ? ln ? ( P V ) - 27.52 ( A ) f ? ? O 2 < 2.304 · 10 - 3 ( 27.52 + Z d + 8 ? ? ln ? ( V P ? ( Z d ) 2.25 ) ) 2 ( B ) wherein: Z is the distance between the metal sheet and the nozzle along the main ejection direction (E), Z being expressed in mm, d is the average height of the outlet of the nozzle along with the running direction of the metal sheet in front of the nozzle, d being expressed in mm, V is the running speed of the metal sheet in front of the nozzle, V being expressed in m·s?1, P is the pressure of the wiping gas in the nozzle, P being expressed in N·m?2, and fO2 is the volume fraction of oxygen in the wiping gas. A metal sheet, part and land motor vehicle are also provided.

Abstract: Provided are a steel sheet with excellent weldability, and a production method therefor. The steel sheet is characterized by having a specific composition and a metallographic structure containing, in terms of an area ratio, ferrite of 25% or more and 65% or less, martensite having iron-based carbides precipitated in the grains of 35% or more and 75% or less, and the balance structure other than the ferrite and the martensite of 20% or less (including 0%) in total, the average grain diameters of the ferrite and the martensite being respectively 5 ?m or lower, the total of concentration of Si and Mn at interface between the ferrite and the martensite being, in terms of an atomic concentration, 5% or more, and having a tensile strength of 900 MPa or higher.

Abstract: The present invention provides an aqueous treatment solution containing sulfate ions SO42? in a concentration greater than or equal to 0.01 mol/l, to treat sheet metal including a steel substrate coated on at least one face with a coating including at least zinc and magnesium to reduce blackening or tarnishing of the sheet metal during storage. The present invention also provides a sheet metal treated with a solution of this type.

Abstract: A high strength steel sheet comprises 0.02 to 0.12 wt % of carbon (C), 0.5 to 2.0 wt % of manganese (Mn), 0.05 to 0.5 wt % of silicon (Si), 0.05 to 1.0 wt % of nickel (Ni), 0.005 to 0.1 wt % of titanium (Ti), 0.005 to 0.5 wt % of aluminum (Al), 0.015 wt % or less of phosphorus (P), 0.015 wt % or less of sulfur (S), and the balance of Fe and other inevitable impurities. The microstructure thereof includes 70% to 90% of ultrafine ferrite and 10% to 30% of MA (martensite/austenite) structure by area fraction, and the yield ratio (YS/TS) thereof is 0.8 or less.

Abstract: A computer-based method of providing control commands of a control command set for manufacturing a three-dimensional object with an additive manufacturing device. The method includes at least the following steps: a step of allocating input data that represent at least a partial surface of the object to be manufactured, where the partial surface has an initial surface texture defined by a set of initial texture parameter values that characterize the geometry of the initial surface texture; a step of determining a set of target texture parameter values that differ from the set of initial texture parameter values, and a step of generating control commands of a control command set to manufacture the partial surface by the additive manufacturing device with a surface texture that is defined by the set of target texture parameter values.

Abstract: A high-strength steel sheet having a high yield ratio and excellent stretch flangeability, and a method for producing the high-strength steel sheet. The high-strength steel sheet has a composition containing, by mass: C: 0.02% or more and less than 0.10%, Si: less than 0.10%, Mn: less than 1.0%, P: 0.10% or less, S: 0.020% or less, Al: 0.01% or more and 0.10% or less, N: 0.010% or less, Nb: 0.005% or more and less than 0.070%, and the balance being Fe and inevitable impurities; and a microstructure including, by area: ferrite: 85% or more, pearlite: 0% to 15%, and a total of martensite, retained austenite and cementite: 0% to 3%. The average crystal grain diameter of the ferrite is 15.0 ?m or less. The grain diameter of a Nb carbide is 5 to 50 nm. The amount of Nb carbide precipitate is 0.005% to 0.050% in terms of volume fraction.

Abstract: A method for producing high-strength galvanized steel sheets having excellent coating adhesion, workability and appearance. The method comprises hot rolling a slab comprising, by mass %, C: 0.05 to 0.30%, Si: 0.1 to 2.0% and Mn: 1.0 to 4.0%, then coiling the steel sheet into a coil at a specific temperature TC, and pickling the steel sheet, cold rolling the hot-rolled steel sheet resulting from the hot rolling, annealing the cold-rolled steel sheet resulting from the cold rolling under specific conditions, and galvanizing the annealed sheet resulting from the annealing in a galvanizing bath containing 0.12 to 0.22 mass % Al.

Abstract: The present invention has as its object to provide a spot welded joint and spot welding method which raise the fracture toughness of spot welded metal to raise the strength of the spot welded joint. In the present invention, there is provided a spot welding method comprising a melt zone forming step forming a melt zone by conduction and, after the melt zone forming step, a solidification step of running a current lower than the current run in the melt zone forming step so as to cause the melt zone to solidify, wherein, in the solidification step, electromagnetic vibration is applied to the melt zone, and a frequency fV of the electromagnetic vibration, a solidification speed ?S when the melt zone solidifies, and an arm interval of dendrites ?D when the melt zone solidifies satisfy 0.2??S/(?D·fV)?4.0.

Abstract: A method for manufacturing a hot press formed part, includes: preparing a hot press forming object comprising a single-ply portion and a two-ply portion; heating the hot press forming object to a temperature range from an Ac3 transformation temperature of a base steel sheet of the first coated steel sheet to 1000° C.; press forming the hot press forming object to obtain a formed body, the press forming being started upon temperatures of the single-ply portion and of the two-ply portion being no higher than solidification points of Zn—Ni coating layers of the first and second coated steel sheets and no lower than an Ar3 transformation temperature of the base steel sheet of the first coated steel sheet; and quenching the formed body to thereby obtain a hot press formed part, in which the hot press forming object has a thickness ratio from 1.4 to 5.0.

Abstract: A method for continuously annealing a steel strip includes annealing the steel strip in a vertical annealing furnace, an atmosphere in the furnace being separated by a partition disposed within a space spanning from the heating zone to the soaking zone. An atmosphere gas is supplied from an outside of the furnace into the furnace to form a furnace gas that is discharged from a steel strip entrance at a lower portion of the heating zone, a part of the furnace gas is sucked and discharged into a refiner including a deoxygenator and a dehumidifier such that oxygen and moisture in the part of the furnace gas are removed to form a gas having a lowered dew point, and the gas having a lowered dew point is returned into the furnace. The method further includes controlling a temperature of the steel strip passing through the partition to a range of 550° C. to 700° C.

Abstract: A high-strength hot-dip galvanized steel sheet that is a steel sheet that includes major components and that contains at least 40 vol. % the sum of bainite and martensite, 8-60 vol. % retained austenite, and less than 40 vol. % ferrite, with the remainder comprising an incidental structure. The hot-dip galvanized steel sheet has, at the interface between the deposit layer formed by hot-dip galvanization and the base steel sheet, an intermetallic compound constituted of Fe, Al, Zn, and incidental impurities and having an average thickness of 0.1-2 ?m, the intermetallic compound having a crystal grain diameter of 0.01-1 ?m. After the deposit layer formed by hot-dip galvanization was removed, the surface of the base steel sheet has an arithmetic average roughness Ra of 0.1-2.0 ?m and gives a roughness curve in which the contour elements have an average length RSm of 5-300 ?m.

Abstract: There is provided a hot-dip galvanized steel sheet and a hot-dip galvannealed steel sheet, which have excellent elongation properties, and methods for manufacturing the hot-dip galvanized steel sheet and the hot-dip galvannealed steel sheet. The present disclosure relates to a hot-dip galvanized steel sheet in which a hot-dip galvanized layer is formed on a surface of abase steel sheet, the hot-dip galvanized steel sheet having excellent elongation properties and being characterized by the composition and the microstructure thereof.

Abstract: The present invention provides a cooling device for a hot-dip plating device provided on an upper side of a plating thickness control device in a conveyance route of a hot-dip plated steel sheet that is conveyed from a plating bath in a vertically upward direction. The cooling device includes: a main cooling device that vertically sprays a main cooling gas to the hot-dip plated steel sheet; and a preliminary cooling device that is provided in a preliminary cooling section between the main cooling device and the plating thickness control device in the conveyance route, and sprays a preliminary cooling gas to a plurality of gas collision positions which are set along the preliminary cooling section.

Abstract: A high-strength galvanized steel sheet having a chemical composition containing, by mass %, C: 0.07% to 0.25%, Si: 0.01% to 3.00%, Mn: 1.5% to 4.0%, P: 0.100% or less, S: 0.02% or less, Al: 0.01% to 1.50%, N: 0.001% to 0.008%, Ti: 0.003% to 0.200%, B: 0.0003% to 0.

Abstract: A high-strength steel sheet having a high yield ratio and a reduced difference in strength between the center and edges of the steel sheet in the width direction. The high-strength steel sheet includes a composition containing, by mass, C: 0.02% or more and less than 0.10%, Si: less than 0.10%, Mn: less than 1.0%, P: 0.10% or less, S: 0.020% or less, Al: 0.01% or more and 0.10% or less, N: 0.010% or less, Nb: 0.005% or more and less than 0.070%, and the balance being Fe and inevitable impurities. Additionally, the steel sheet has a microstructure including, by area, ferrite: 90% or more, pearlite: 0% to 10%, and the total of martensite, retained austenite, and cementite: 0% to 3%. The average crystal grain diameter dC of the ferrite at the center of the steel sheet in the width direction is 15.0 ?m or less.

Abstract: Provided is a Zn—A—Mg coated steel sheet having a plated layer including from 4 to 22% by mass of Al, from 1.0 to 6.5% by mass of Mg, from 0.001 to 1.000% by mass of Si, as well as Zn and impurities as the balance, wherein the structure of the plated layer contains an Al primary crystal, the Al primary crystal including: a cellular dendrite-shaped first Al primary crystal and a second axis spacing of from 0.5 to 2.0 ?m; a minute equi-axed dendrite-shaped second Al primary crystal and a second axis spacing of from 0.5 to 2.0 ?m; and a petal-shaped third Al primary crystal with a principal axis length of from 0.5 to 3.0 ?m and a ternary eutectic structure of Al, Zn, and Mg2Zn11 as a structure other than the Al primary crystal.

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 cold rolled and hot dip coated steel sheet presenting a tensile strength above 1000?50×Al MPa, a uniform elongation above 15% and a low density is provided. The steel includes, by weight percent: 0.1?C?0.5%, 3.5?Mn?10.0%, 0?Al?9.0%, Si?5.0%, Ti?0.2%, V?0.2%, Nb?0.2%, S?0.004%, P?0.025%, 0.5?Si+Al?9.0%, B?0.0035, Cr?1%, The balance being Fe and impurities and the microstructure containing 25% to 90% of ferrite, 10% to 50% of austenite, kappa precipitates lower than 5% and martensite lower than 25%. The steel is able to be coated using total oxidation.

Abstract: The present invention provides a high-strength steel sheet excellent in impact resistance. The high-strength steel sheet contains predetermined contents of C, Si, Mn, P, S, Al, Ti, N, and O, with the balance being iron and inevitable impurities, and has a steel sheet structure in which, in a ? thickness to ? thickness region across ¼ of a sheet thickness, 1 to 8% retained austenite is contained in volume fraction, an average aspect ratio of the retained austenite is 2.0 or less, an amount of solid-solution Mn in the retained austenite is 1.1 times an average amount of Mn or more, and TiN grains having a 0.5 ?m average grain diameter or less are contained, and a density of AlN grains with a 1 ?m grain diameter or more is 1.0 pieces/mm2 or less, wherein a maximum tensile strength is 900 MPa or more.

Abstract: A hot-rolled steel sheet includes, as a chemical composition, by mass %, C: 0.030% to 0.10%, Mn: 0.5% to 2.5%, and Si+Al: 0.100% to 2.5%, in which the steel sheet has a microstructure including, by area fraction, ferrite: 80% or more, martensite: 3% to 15.0%, and pearlite: less than 3.0%, in which a number density of martensite having an equivalent circle diameter of 3 ?m or more at a position which is at a depth of ¼ of the steel sheet thickness from the surface of the steel sheet, is 5.0 pieces/10000 ?m2 or less, and the following Expression (1) is satisfied. R/DM2?1.00??Expression (1) Here, R is an average martensite interval (?m) defined by the following Expression (2), and DM is a martensite average diameter (?m). R={12.5×(?/6VM)0.5?(?)0.5}×DM??Expression (2) Here, VM is a martensite area fraction (%) and DM is the martensite average diameter (?m).

Abstract: A hot-pressed steel sheet member includes a specific chemical composition and further includes a steel structure in which an area ratio of ferrite in a surface layer portion ranging from a surface to 15 ?m in depth is greater than 1.20 times an area ratio of ferrite in an inner layer portion being a portion excluding the surface layer portion, and the inner layer portion contains a steel structure represented, in area %, ferrite: 10% to 70%, martensite: 30% to 90%, and a total area ratio of ferrite and martensite: 90% to 100%. A tensile strength of the hot-pressed steel sheet member is 980 MPa or more.

Abstract: A method of manufacturing a galvanized steel sheet includes a two-stage temperature raising process which includes: primary heating the sheet from 200° C. to an intermediate temperature of 500 to 800° C. at a primary average heating rate of 5 to 50° C./second at an excess air ratio of 1.10 to 1.20 maintained up to the intermediate temperature; secondary heating the sheet from the intermediate temperature to an annealing temperature of 730 to 900° C. at a secondary average heating rate of 0.1 to 10° C./second at an excess air ratio of less than 1.10 maintained up to the annealing temperature; holding the sheet to the annealing temperature for 10 to 500 seconds; cooling the sheet to 450 to 550° C. at an average cooling rate of 1 to 30° C./second; and subjecting the sheet to a galvanizing process and, optionally, an alloying process.

Abstract: The present invention provides a hot-dip galvanized steel sheet that is excellent in plating wettability and plating adhesiveness even when a base steel sheet contains Si and Mn, and a manufacturing method of the same. The hot-dip galvanized steel sheet according to the present invention includes a base steel sheet containing Si, Mn, and other predetermined components, and a hot-dip galvanizing layer formed on at least one surface of the base steel sheet. In the base steel sheet, a value of HA representing average hardness in a surface layer ranging from an interface between the base steel sheet and the hot-dip galvanizing layer to 50 ?m in depth and a value of HB representing average hardness in a deep portion ranging from the interface to greater than 50 ?m in depth satisfy all the following three relational expressions. 50?HA?500??(1) 50?HB?500??(2) 0.5?HA/HB?0.

Abstract: A metallic flat product is disclosed which is subjected to surface finishing by hot-dip coating and which is preferably composed of steel. The metallic flat product includes a metallic alloy layer (11) and a metallic surface layer (12?), which metallic alloy layer and metallic surface layer differ from one another in terms of their chemical composition. The two layers (11, 12?) are produced in a one process step and define a continuous transition region (13) in which a mixture of the two different chemical compositions is present. The metallic alloy layer (11) has a thickness of less than 8 ?m, preferably less than 6 ?m, and the surface layer (12?) is formed from aluminum or zinc. The flat product has an improved coating, by means of which the flat product more effectively satisfies the requirements with regard to good deformability and has good anti-corrosion protection.

Abstract: A high-strength cold-rolled steel sheet has a composition and a microstructure. The microstructure comprises: ferrite having an average grain size of 5 ?m or less and a volume fraction of 3% to 20%, retained austenite having a volume fraction of 5% to 20%, and martensite having a volume fraction of 5% to 20%, the remainder being bainite and/or tempered martensite. The total number of retained austenite with a grain size of 2 ?m or less, martensite with a grain size of 2 ?m or less, or a mixed phase thereof is 150 or more per 2,000 ?m2 of a thickness cross section parallel to the rolling direction of the steel sheet.

Abstract: Disclosed is a high-strength steel sheet having a tensile strength of 1180 MPa or more and having satisfactory seam weldability. The steel sheet has a chemical composition of C: 0.12% to 0.40%, Si: 0.003% to 0.5%, Mn 0.01% to 1.5%, Al: 0.032% to 0.15%, N: 0.01% or less, P: 0.02% or less, S: 0.01% or less, Ti: 0.01% to 0.2% or less, and B: 0.0001% to 0.01%, with the remainder including iron and inevitable impurities, has a Ceq1 (=C+Mn/5+Si/13) of 0.50% or less, and has a steel structure of a martensite single-phase structure.