Abstract: A steel sheet, including: as chemical components, by mass %, 0.05% to 0.35% of C; 0.05% to 2.0% of Si; 0.8% to 3.0% of Mn; 0.01% to 2.0% of Al; equal to or less than 0.1% of P; equal to or less than 0.05% of S; equal to or less than 0.01% of N; and the balance including iron and inevitable impurities, wherein an area ratio of equal to or higher than 50% of a total of a ferrite phase, a bainite phase, and a tempered martensite phase is contained, an area ratio of equal to or higher than 3% of a retained austenite phase is contained, and crystal grains of the retained austenite phase having a number ratio of equal to or higher than 50% satisfy Expression 1, assuming carbon concentration at a position of center of gravity is Cgc and a carbon concentration at a grain boundary is Cgb.

Abstract: Methods for welding a first metal part to a second metal part by a solid state process to form a welded article having at least a welded region are provided herein. The welded region of the weld is post-weld aged by heating it to a set temperature for a set time and compressing the weld.

Abstract: A steel sheet has the chemical composition containing, by mass %, C: 0.04 to 0.13%, Si: 0.9 to 2.3%, Mn: 0.8 to 1.8%, P: 0.1% or less, S: 0.01% or less, Al: 0.1% or less, N: 0.008% or less, the remainder being Fe and the inevitable impurities and a microstructure including, in terms of area ratio, a ferrite phase of 80% or more, a bainitic ferrite phase of 1.0% or more, a pearlite phase of 1.0 to 10.0%, and a martensite phase of 1.0% or more and less than 5.0%, wherein the mean grain size of ferrite is 14 ?m or less, the mean grain size of martensite is 4 ?m or less, the mean free path of martensite is 3 ?m or more, the Vickers hardness of ferrite is 140 or more, and the relationship area ratio of martensite/(area ratio of bainitic ferrite+area ratio of pearlite) 0.6 is satisfied.

Abstract: The present disclosure relates to a dual phase steel sheet and a method of manufacturing the same. The steel sheet comprises C: 0.05˜0.10 % wt %, Si: 0.03˜0.50 wt %, Mn: 1.50˜2.00 wt %, P: greater than 0 wt %˜0.03 wt %, S: greater than 0 wt %˜0.003 wt %, Al: 0.03˜0.50 wt %, Cr:0.1˜0.2 wt %, Mo: 0.1˜0.20 wt %, Nb: 0.02˜0.04 wt %, B: greater than 0 wt %˜0.005 wt %, N: greater than 0 wt %˜0.01 wt %, and the balance of Fe and other unavoidable impurities. To impart excellent formability, bake hardenability, dent resistance, high Ri value and plating characteristics to the steel sheet for exterior and interior panels of automobiles, the steel sheet is processed to have a dual phase structure through cold rolling, annealing, and hot-dip galvanizing.

Abstract: A steel sheet excellent in mechanical strength, workability and thermal stability and suited for use as a raw material in such fields of manufacturing automobiles, household electric appliances and machine structures and of constructing buildings, and a manufacturing method thereof are provided. The steel sheet is a hot-rolled steel sheet of carbon steel or low-alloy steel, the main phase of which is ferrite, and is characterized in that the average ferrite crystal grain diameter D (?m) at the depth of ¼ of the sheet thickness from the steel sheet surface satisfies the relations respectively defined by the formulas (1) and (2) given below and the increase rate X (?m/min) in average ferrite crystal grain diameter at 700° C. at the depth of ¼ of the sheet thickness from the steel sheet surface and said average crystal grain diameter D (?m) satisfy the relation defined by the formula (3) given below: 1.2?D?7??formula (1) D?2.7+5000/(5+350·C+40·Mn)2??formula (2) D·X?0.

Abstract: A steel part having a homogeneous multiphase microstructure in each region of the part, the microstructure containing ferrite, wherein the steel part is obtained by a process involving: cutting a blank from a strip of steel, having a specified composition; optionally, the blank undergoes prior cold deformation; the blank is heated to reach a soak temperature Ts above Ac1 but below Ac3 and held at this soak temperature Ts for a soak time ts adjusted so that the steel, after the blank has been heated, has an austenite content equal to or greater than 25% by area; the heated blank is transferred into a forming tool to hot-form the part; and the part is cooled within the tool at a cooling rate V such that the microstructure of the steel, after cooling the part, is a multiphase microstructure containing ferrite and being homogeneous in each region of the part.

Abstract: The present invention provides: a high-strength high-ductility hot-dip galvanized steel sheet and hot-dip galvannealed steel sheet having high fatigue resistance and corrosion resistance; a high-strength hot-dip galvanized steel sheet excellent in ductility, which improves non-plating defects and plating adhesion after severe deformation, and a method of producing the same; a high-strength and high-ductility hot-dip galvanized steel sheet having high fatigue resistance and corrosion resistance; a high-strength hot-dip galvanized steel sheet and hot-dip galvannealed steel sheet having superior appearance and workability, which suppresses the generation of non-plating defects, and a method of producing the same; and a high-strength hot-dip galvannealed steel sheet and a high-strength hot-dip galvanized steel sheet, which suppress non-plating defects and surface defects and have both corrosion resistance, in particular corrosion resistance in an environment containing chlorine ion, and high ductility, and a meth

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 method by which a flat steel product containing 2-35 wt. % of Mn can be provided with a coating of Zn which adheres well by annealing at an annealing temperature Ta of 600-1100° C. for an annealing time of 10-240 s under an annealing atmosphere which has a reducing effect on the FeO present on the flat steel product and an oxidising effect on the Mn contained in the steel substrate thereby forming a layer of Mn mixed oxide which covers the flat steel product at least in sections and then cooling the flat steel product to a temperature for bath entry and conveying it through a bath of molten Zn saturated within iron at a temperature of 420-520° C., within a dip time of 0.1-10 s.

Abstract: A high-strength galvanized steel sheet has a low YP, good stretch flangeability, and excellent corrosion resistance and contains, on a percent by mass basis, more than 0.015% to less than 0.10% of C, 0.5% or less of Si, 1.0% to 1.9% of Mn, 0.015% to 0.050% of P, 0.03% or less of S, 0.01% to 0.5% of sol. Al, 0.005% or less of N, less than 0.40% of Cr, 0.005% or less of B, less than 0.15% of Mo, 0.4% or less of V, and less than 0.020% of Ti, in which 2.2?[Mneq]?3.1 and [% Mn]+3.3[% Mo]?1.9, and [% Mn]+3.3 [% Mo])/(1.3[% Cr]+8[% P]+150B*)<3.5 are satisfied.

Abstract: The present invention provides a high-strength galvanized steel sheet having excellent ductility, stretch flangeability, and fatigue resistance, and a method for manufacturing the same. A high-strength galvannealed steel sheet having excellent formability and fatigue resistance is characterized in that the steel sheet is composed of steel having a composition containing, by % by mass, C: 0.05% to 0.3%, Si: 0.5% to 2.5%, Mn: 1.0% to 3.5%, P: 0.003% to 0.100%, S: 0.02% or less, Al: 0.010% to 0.1%, and the balance including iron and unavoidable impurities, and the steel sheet has a microstructure containing 50% or more of ferrite, 5% to 35% of martensite, and 2% to 15% of pearlite in terms of an area ratio, the martensite having an average gain size of 3 ?m or less and an average distance of 5 ?m or less between adjacent martensite grains.

Abstract: A method for producing a high-strength hot-dip galvanized steel sheet includes a steel sheet containing, in percent by mass, 0.01% to 0.18% of C, 0.02% to 2.0% of Si, 1.0% to 3.0% of Mn, 0.001% to 1.0% of Al, 0.005% to 0.060% of P, 0.01% or less of S, and the balance being Fe and incidental impurities, and a galvanized coating layer on each surface of the steel sheet with a coating weight of 20 to 120 g/m2 per surface, in which, when the steel sheet is subjected to annealing and a hot-dip galvanizing treatment in a continuous hot-dip galvanizing line, the dew point of the atmosphere is controlled to ?40° C. or lower in the annealing furnace temperature range of 750° C. or higher.

Abstract: Disclosed is a high-strength steel sheet which has a predetermined component composition, structurally has a ferrite matrix structure and bainitic and martensitic second phase structures, and has a ferrite fraction of from 50 to 86 percent by area, a bainite fraction of from 10 to 30 percent by area, and a martensite fraction of from 4 to 20 percent by area, relative to the entire structure, in which the bainite area fraction is larger than the martensite area fraction, the ferrite has an average grain size of 2.0 to 5.0 ?m, and the ratio of the average ferrite hardness (Hv) to the tensile strength (MPa) of the steel sheet is equal to or more than 0.25. The steel sheet excels both in TS-EL balance and TS-? balance at high strengths on the order of 590 to 780 MPa.

Abstract: A high strength galvanized steel sheet with excellent workability, having a component composition containing C: 0.04% or more, and 0.15% or less, Si: 0.7% or more, and 2.3% or less, Mn: 0.8% or more, and 2.2% or less, P: 0.1% or less, S: 0.01% or less, Al: 0.1% or less, N: 0.008% or less, and the remainder composed of iron and incidental impurities on a percent by mass basis, and a microstructure including 70% or more of ferrite phase, 2% or more, and 10% or less of bainite phase, and 0% or more, and 12% or less of pearlite phase on an area fraction basis and 1% or more, and 8% or less of retained austenite phase on a volume fraction basis, wherein an average crystal grain diameter of ferrite is 18 ?m or less and an average crystal grain diameter of retained austenite is 2 ?m or less.

Abstract: The high strength galvanized steel sheet contains C: more than 0.015% and lower than 0.100%, Si: 0.3% or lower, Mn: lower than 1.90%, P: 0.015% or more and 0.05% or lower, S: 0.03% or lower, sol.Al: 0.01% or more and 0.5% or lower, N: 0.005% or lower, Cr: lower than 0.30%, B: 0.0003% or more and 0.005% or lower, and Ti: lower than 0.014% in terms of mass %, and satisfies 2.2?[Mneq]?3.1 and 0.42?8[% P]+150B*?0.73. The steel microstructure contains ferrite and a second phase, in which the second phase area ratio is 3 to 15%, the ratio of the area ratio of martensite and retained ? to the second phase area ratio is more than 70%, and 50% or more of the area ratio of the second phase exists in the grain boundary triple point.

Abstract: A method of making hot rolled steel sheet having a dual phase microstructure with a martensite phase of less than 35% by volume and a ferrite phase of more than 50% by volume and a composition containing by percent weight: 0.01?C?0.2; 0.3?Mn?3; 0.2?Si?2; 0.2?Cr+Ni?2; 0.01?Al?0.10; Mo less than about 0.2%, 0.0005?Ca?0.01, with the balance iron and incidental ingredients. Hot rolled sheet for cold rolling, the silicon range may be from about 0.05% to about 2%, and the amount of molybdenum may be up to 0.5%. Also, the hot rolled steel sheet has a tensile strength of at least 500 megapascals, a hole expansion ratio more than about 50%, and a yield strength/tensile strength ratio less than 70%.

Abstract: Provided is a method for manufacturing a high-strength galvanized steel sheet, made from a steel sheet containing Si and/or Mn, having excellent exfoliation resistance during heavy machining. When a steel sheet containing 0.01% to 0.18% C, 0.02% to 2.0% Si, 1.0% to 3.0% Mn, 0.001% to 1.0% Al, 0.005% to 0.060% P, and 0.01% or less S on a mass basis, the remainder being Fe and unavoidable impurities, is annealed and galvanized in a continuous galvanizing line, a temperature region with a furnace temperature of A° C. to B° C. (600?A?780 and 800?B?900) is performed at an atmosphere dew-point temperature of ?5° C. or higher in a heating process.

Abstract: The high-strength galvanized steel sheet having excellent formability has a component composition containing, on the basis of mass percent, 0.05 to 0.2% C, 0.5 to 2.5% Si, 1.5 to 3.0% Mn, 0.001 to 0.05% P, 0.0001 to 0.01% S, 0.001 to 0.1% Al, and 0.0005 to 0.01% N, the balance being Fe and incidental impurities; and the steel sheet has a microstructure including a ferritic phase and a martensitic phase including a tempered-martensitic phase, the ferritic phase having an area fraction of 30% or more relative to an entirety of the microstructure, the martensitic phase having an area fraction of 30 to 50% relative to the entirety of the microstructure, and the tempered-martensitic phase having an area fraction of 70% or more relative to an entirety of the martensitic phase.

Abstract: A heat treatment or heat soak furnace for use in both galvannealing and galvanizing processes including a heating apparatus configured to supply heat and remove heat. The heating apparatus may draw hot air from the exhaust of a direct fire strip annealing furnace, gas burners or electric heat exchangers as necessary. The furnace also may include a plurality of cooling mechanisms in order to ensure heat is removed and the temperature within the furnace regulated. In addition, the furnace may include baffles configured to allow portions of the interior of the furnace to be separated into different temperature zones.

Abstract: A high-strength quenched formed article has a zinc plating layer which is formed at a post-quenching formed steel sheet surface, and which contains 30 g/m2 or more of a phase that contains 5% or more by mass but 30% or less by mass of Fe, and which also contains 0.15% or more by mass but less than 2% by mass of at least one of Al and Si in a separate fashion or a composite fashion, and contains Zn, which makes up substantially a rest portion of the zinc plating layer, and an inevitable impurity, wherein the high-strength quenched formed article has a high-strength portion having a post-quenching-formation tensile strength of 1000 MPa or more, and a low-strength portion having a post-quenching-formation tensile strength of 800 MPa or less.

Abstract: The invention is directed to providing, for application in automobiles, construction materials, household appliances and the like, high-strength sheets excellent in formability properties such as hole expansibility and ductility, and also in fatigue resistance, characterized in comprising, in specified contents expressed in mass %, C, Si, Mn, P, S, Al, N and O and a balance of iron and unavoidable impurities, and having a steel sheet structure composed mainly of ferrite and hard structures, a crystal orientation difference between some ferrite adjacent to hard structures and the hard structures of less than 9°, and a maximum tensile strength of 540 MPa or greater.

Abstract: Steel sheet having a composition of ingredients containing substantially, by mass %, C: 0.005 to 0.200%, Si: 2.50% or less, Mn: 0.10 to 3.00%, N: 0.0100% or less, Nb: 0.005 to 0.100%, and Ti: 0.002 to 0.150% and satisfying the relationship of Ti?48/14×N?0.0005, having a sum of the X-ray random intensity ratios of the {100}<001> orientation and the {110}<001> orientation of a ? sheet thickness part of 5 or less, having a sum of the maximum value of the X-ray random intensity ratios of the {110}<111> to {110}<112> orientation group and the X-ray random intensity ratios of the {211}<111> orientation of 5 or more, and having a high rolling direction Young's modulus measured by the static tension method and a method of production of the same are provided.

Abstract: A method for manufacturing a coated part having very high mechanical properties using hot forming techniques. The method includes the steps of 1—providing a steel strip; 2—coating the steel strip with a layer of zinc or zinc alloy; 3—heating the coated steel to a temperature between 300° C. and the Ac1 temperature of the steel; 4—cooling the coated steel; 5—cutting a blank from the strip after step 1, 2, 3 or 4; 6—heating the blank to a temperature above the Ac1 temperature of the steel; 7—hot forming the blank into a part; and 8—hardening the hot formed part. The method can also be performed without step 4. The method can also be used for the indirect hot formed method. The method also relates to a method for manufacturing a coated steel strip, and to a coated steel strip, blank or part and a hot formed part.

Abstract: The invention relates to a method for producing a hardened steel part having a cathodic corrosion protection, whereby a) a coating is applied to a sheet made of a hardenable steel alloy in a continuous coating process; b) the coating is essentially comprised of zinc; c) the coating additionally contains one or more oxygen-affine elements in a total amount of 0.1% by weight to 15% by weight with regard to the entire coating; d) the coated steel sheet is then, at least in partial areas and with the admission of atmospheric oxygen, brought to a temperature necessary for hardening and is heated until it undergoes a microstructural change necessary for hardening, whereby; e) a superficial skin is formed on the coating from an oxide of the oxygen-affine element(s), and; f) the sheet is shaped before or after heating, and; g) the sheet is cooled after sufficient heating, whereby the cooling rate is calculated in order to achieve a hardening of the sheet alloy.

Abstract: A galvanized steel sheet includes a basal steel sheet (BSS) containing C: 0.01-0.15%, Si: 0.001-2.0%, Mn: 0.1-3.0%, Al: 0.001-1.00, P: 0.005-0.060%, and S?0.01% (all % by mass), balance is Fe and unavoidable impurities; zinc plating layers on both sides of the BSS with 20-120 g/m2 plating/side; one or more oxides selected from Fe, Si, Mn, Al, and P oxides and existing in steel sheet superficial portions in direct contact with zinc plating layers and extending from each surface of the BSS to 100 ?m deep, with the total amount of the oxides per side 0.01-0.5 g/m2; and a crystalline oxide in the regions from each surface of the BSS to 10 ?m depth, which are also located in direct contact with the zinc plating layers, the crystalline oxide including Fe crystal grains in which Si and Mn atoms are distributed in the regions from grain boundaries to 1 ?m deep.

Abstract: The present disclosure relates to a high strength steel sheet having good wettability, a tensile strength of 590 MPa or more and a strength-ductility balance (TS×El) of 16,520 MPa·% or more, and a manufacturing method thereof. The high strength steel comprises, in % by weight, C: 0.03˜0.1%, Si: 0.005˜0.105%, Mn: 1.0˜3.0%, P: 0.005˜0.04%, S: 0.003% or less, N: 0.003˜0.008%, Al: 0.05˜0.4%, Mo or Cr satisfying the inequality 10?50·[Mo %]+100·[Cr %]?30, at least one of Ti: 0.005˜0.020%, V: 0.005˜0.050% and B: 0.0005˜0.0015%, and the balance of Fe and unavoidable impurities, wherein a microstructure of the steel sheet is a multi-phase structure comprising, in an area ratio of cross-sectional structure, 70% or more ferrite phase having a Vickers hardness Hv of 120˜250 and 10% or more martensite phase having a Vickers hardness Hv of 321˜555.

Abstract: A high-strength galvanized steel sheet has excellent mechanical properties such as a TS of 1200 MPa or more, an El of 13% or more, and a hole expansion ratio of 50% or more and a method for manufacturing the same. A high-strength galvanized steel sheet excellent in formability contains 0.05% to 0.5% C, 0.01% to 2.5% Si, 0.5% to 3.5% Mn, 0.003% to 0.100% P, 0.02% or less S, and 0.010% to 0.5% Al on a mass basis, the remainder being Fe and unavoidable impurities, and has a microstructure which contains 0% to 10% ferrite, 0% to 10% martensite, and 60% to 95% tempered martensite on an area basis as determined by structure observation and which further contains 5% to 20% retained austenite as determined by X-ray diffractometry.

Abstract: The present invention relates to a hot dip galvanized steel sheet and a manufacturing method thereof. The hot dip galvanize steel sheet includes a steel sheet including a martensitic structure as a matrix, and a hot dip galvanized layer formed on the steel sheet. The steel sheet includes C of 0.05 wt % to 0.30 wt %, Mn of 0.5 wt % to 3.5 wt %, Si of 0.1 wt % to 0.8 wt %, Al of 0.01 wt % to 1.5 wt %, Cr of 0.01 wt % to 1.5 wt %, Mo of 0.01 wt % to 1.5 wt %, Ti of 0.001 wt % to 0.10 wt %, N of 5 ppm to 120 ppm, B of 3 ppm to 80 ppm, an impurity, and the remainder of Fe.

Abstract: The invention concerns a very high mechanical strength steel, whereof the chemical composition comprises in wt. %: 0.006%=C=0250%; 0.400%=Mn=0.950%; Si=0.300%; Cr=0.300%; 0.100%=Mo=0.500%; 0.020%=AI=0.100%; P=0.100%; B=0.010%; Ti=0.050%, the rest being iron and impurities resulting from preparation. The invention also concerns a method for making a sheet of said steel coated with zinc or zinc alloy.

Abstract: A high strength steel sheet having composition includes, on a percent by mass basis, C: 0.17% to 0.73%; Si: 3.0% or less; Mn: 0.5% to 3.0%; P: 0.1% or less; S: 0.07% or less; Al: 3.0% or less; and N: 0.010% or less, satisfies Si+Al?0.7%, and the remainder includes Fe and incidental impurities, with a microstructure that has an area percentage of a total amount of lower bainite and whole martensite 10% to 90% relative to the whole steel sheet microstructure, an amount of retained austenite is 5% to 50%, an area percentage of bainitic ferrite in upper bainite is 5% or more relative to the whole steel sheet microstructure, as-quenched martensite is 75% or less of the total amount of lower bainite and whole martensite, and an area percentage of polygonal ferrite is 10% or less relative to the whole steel sheet microstructure, an average amount of C in retained austenite is 0.70% or more, and tensile strength is 980 MPa or more.

Abstract: A high-strength steel sheet has good ductility and stretch-flangeability and has a tensile strength (TS) of 980 MPa or more. The steel sheet contains 0.17%-0.73% C, 3.0% or less Si, 0.5%-3.0% Mn, 0.1% or less P, 0.07% or less S, 3.0% or less Al, and 0.010% or less N, in which Si+Al is 0.7% or more.

Abstract: Method for use when galvannealing a steel material (1), in which the material (1), in a first step, is preheated to a first process temperature and is coated with a layer of a liquid alloying metal (3), in a second step is further heated to a second, higher process temperature, and in a third step is kept at the second process temperature during a predetermined time period so that the alloying metal coating at least partially is caused to alloy with the steel material (1). The heating in the second step is caused to be carried out by one or several DFI burners (5).

Abstract: A high strength galvanized steel sheet with excellent appearance that does not have non-uniformity of coating or coating defects or allow linear defects to occur after press forming includes a steel sheet having a ferrite single-phase structure and having a composition containing 0.0005% to 0.0040% by mass of C; 0.1% to 1.0% by mass of Si; 1.0% to 2.5% by mass of Mn; 0.01% to 0.20% by mass of P; 0.015% by mass of less of S; 0.01% to 0.10% by mass of Al; 0.0005% to 0.0070% by mass of N; 0.010% to 0.080% by mass of Ti; 0.0005% to 0.0020% by mass of B; 0.05% to 0.50% by mass of Cu; 0.03% to 0.50% by mass of Ni; and the balance of Fe and incidental impurities.

Abstract: A high-strength galvanized steel sheet has a TS of at least 590 MPa and excellent ductility and stretch flangeability and a method for manufacturing the high-strength galvanized steel sheet. The galvanized steel sheet contains, on the basis of mass percent, C: 0.05% to 0.3%, Si: 0.01% to 2.5%, Mn: 0.5% to 3.5%, P: 0.003% to 0.100% or less, S: 0.02% or less, and Al: 0.010% to 1.5%. The total of Si and Al is 0.5% to 2.5%. The remainder are iron and incidental impurities, contain 20% or more of ferrite phase, 10% or less of martensite phase, and 10% to 60% of tempered martensite, on the basis of area percent, and 3% to 10% of retained austenite phase on the basis of volume fraction. The retained austenite has an average grain size of 2.0 ?m or less.

Abstract: A steel sheet having (a) a dual phase microstructure with a martensite phase and a ferrite phase and (b) a composition containing by percent weight: 0.01?C?0.2; 0.3?Mn?3; 0.05?Si?2; 0.2?Cr+Ni?2; 0.01?Al?0.10; 0.0005?Ca?0.01, with the balance of the composition being iron and incidental ingredients. Also, the steel sheet is made by a batch annealing method, and has a tensile strength of at least approximately 400 megapascals and an n-value of at least approximately 0.175.

Abstract: A high tensile steel sheet having 980 MPa or higher tensile strength with excellent elongation and stretch-flange formability, suitable for the press-forming of complex cross sectional shape such as automobile parts, is manufactured by adjusting the steel to consist essential of a ferrite single phase structure, to precipitate carbide containing Ti, Mo, and V, of smaller than 10 nm of average particle size, in dispersed state, and to have an average composition of the carbide containing Ti, Mo, and V satisfying [V/(Ti+Mo+V)?0.3 (atomic ratio].

Abstract: A cold rolled steel sheet and a hot dip galvanized steel sheet, which have high strength and elongation, such as a tensile strength of 980 MPa or more and an elongation of 28% or more, and excellent delayed fracture resistance, and manufacturing methods thereof. The cold rolled steel sheet has a composition including 0.05 to 0.3 weight percent C, 0.3 to 1.6 weight percent. Si, 4.0 to 7.0 weight percent Mn, 0.5 to 2.0 weight percent Al, 0.01 to 0.1 weight percent Cr, 0.02 to 0.1 weight percent Ni and 0.005 to 0.03 weight percent Ti, 5 to 30 ppm B, 0.01 to 0.03 weight percent Sb, 0.008 weight percent or less S, balance Fe and impurities. The hot dip galvanized steel sheet has a hot dip galvanized layer or a hot dip galvannealed layer on the cold rolled steel sheet.

Abstract: There are provided steel sheets which have a tensile strength of 780-980 MPa and an elongation of 28% or higher and are free of edge cracks. The high-strength steel sheet includes, by wt %, 0.1-0.25% C, 1.0-1.9% Si, 1.5-2.5% Mn, 0.5-1.6% Al, 0.005-0.03% Ti, 5-30 ppm B, 0.01-0.03% Sb and a balance of Fe and inevitable impurities, and satisfying 1.75%?Si+Al?3.25%.

Abstract: The present disclosure relates to a dual phase steel sheet and a method of manufacturing the same. The steel sheet comprises C: 0.05˜0.10% wt %, Si: 0.03˜0.50 wt %, Mn: 1.50˜2.00 wt %, P: greater than 0 wt %˜0.03 wt %, S: greater than 0 wt %˜0.003 wt %, Al: 0.03˜0.50 wt %, Cr: 0.1˜0.2 wt %, Mo: 0.1˜0.20 wt %, Nb: 0.02˜0.04 wt %, B: greater than 0 wt %˜0.005 wt %, N: greater than 0 wt %˜0.01 wt %, and the balance of Fe and other unavoidable impurities. To impart excellent formability, bake hardenability, dent resistance, high Ri value and plating characteristics to the steel sheet for exterior and interior panels of automobiles, the steel sheet is processed to have a dual phase structure through cold rolling, annealing, and hot-dip galvanizing.

Abstract: Coating steel strips comprising, in % by weight, C: ?1.6%, Mn: 6-30%, Al: ?10%, Ni: ?10%, Cr: ?10%, Si: ?8%, Cu: ?3%, Nb: ?0.6%, Ti: ?0.3%, V: ?0.3%, P: ?0.1%, B: ?0.01%, the rest being iron and unavoidable impurities, and a method of forming steel strips are described. Up to now, such steel strips were not adequately coatable, with a metal coating ensuring outstanding corrosion-resistance and good welding properties. This is ensured by applying an aluminium layer to the steel strip before final annealing and applying the metal coating to said aluminium layer after final annealing.

Abstract: The invention relates to a method for producing coated spring-loaded steel rails especially for windshield wipers comprising a rubber or elastomer wiper blade, wherein a cold-rolled steel rail blank is provided with a zinc layer, whereafter a zinc-containing anchor layer is produced, and a coating made of a polymerizable coating powder is deposited on the anchor layer and partially cured.

Abstract: A high strength galvanized steel sheet has a TS of 590 MPa or more and excellent processability. The component composition contains, by mass %, C: 0.05% to 0.3%, Si: 0.7% to 2.7%, Mn: 0.5% to 2.8%, P: 0.1% or lower, S: 0.01% or lower, Al: 0.1% or lower, and N: 0.008% or lower, and the balance: Fe or inevitable impurities. The microstructure contains, in terms of area ratio, ferrite phases: 30% to 90%, bainite phases: 3% to 30%, and martensite phases: 5% to 40%, in which, among the martensite phases, martensite phases having an aspect ratio of 3 or more are present in a proportion of 30% or more.

Abstract: The invention is directed to providing, for application in automobiles, construction materials, household appliances and the like, high-strength sheets excellent in formability properties such as hole expansibility and ductility, and also in fatigue resistance, characterized in comprising, in specified contents expressed in mass %, C, Si, Mn, P, S, Al, N and O and a balance of iron and unavoidable impurities, and having a steel sheet structure composed mainly of ferrite and hard structures, a crystal orientation difference between some ferrite adjacent to hard structures and the hard structures of less than 9°, and a maximum tensile strength of 540 MPa or greater.

Abstract: A steel sheet excellent in mechanical strength, workability and thermal stability and suited for use as a raw material in such fields of manufacturing automobiles, household electric appliances, machine structures, and of constructing buildings, and a manufacturing method thereof is provided. The steel sheet is a hot-rolled steel sheet of a carbon steel or low-alloy steel, the main phase of which is ferrite, and is characterized in that the average ferrite crystal grain diameter D(?m) at the depth of ¼ of the sheet thickness from the steel sheet surface satisfies the relations respectively defined by formulas (1) and (2) given below and the increase rate X (?m/min) in average ferrite crystal grain diameter at 700° C. at the depth of ¼ of the sheet thickness from the steel sheet surface and said average crystal grain diameter D(?m) satisfy the relation defined by the formula (3) given below: 1.2?D?7??formula (1) D?2.7+5000/(5+350·C+40·Mn)2??formula (2) D·X?0.

Abstract: A steel flat product having a Zn—Mg—Al coating. The coating, which in addition to zinc and unavoidable impurities, comprises in wt. %: Mg: 4-8%, Al: 0.5-1.8% and optionally one or more of the following: Si: <2%, Pb: <0.1%, Ti: <0.2%, Ni: <1%, Cu: <1%, Co: <0.3%, Mn: <0.5%, Cr: <0.2%, Sr: <0.5%, Fe: <3%, B: <0.1%, Bi: <0.1%, Cd: <0.1%, REM<0.2%, and Sn<0.5%. The steel flat product according to the invention is not only outstandingly protected against corrosion, but also welds well and coats well with an organic layer applied subsequently. The invention also relates to a method for producing a steel flat product having a Zn—Mg—Al coating.

Abstract: A method for coating a hot-rolled or cold-rolled steel flat product, containing 6-30% wt. Mn, with a metallic protective layer by hot-clip coating in a melt bath. The coating, achieved with increased production reliability, is optimised by the steel flat product being subjected to a pickling treatment in which the manganese oxide adhering to the steel flat product is essentially fully removed in the pickling bath before the steel flat product enters the melt bath.

Abstract: This cold-rolled steel sheet includes, in terms of mass %, C: not less than 0.05% and not more than 0.095%, Cr: not less than 0.15% and not more than 2.0%, B: not less than 0.0003% and not more than 0.01%, Si: not less than 0.3% and not more than 2.0%, Mn: not less than 1.7% and not more than 2.6%, Ti: not less than 0.005% and not more than 0.14%, P: not more than 0.03%, S: not more than 0.01%, Al: not more than 0.1%, N: less than 0.005%, O: not less than 0.0005% and not more than 0.005%, and contains as the remainder, iron and unavoidable impurities, wherein the microstructure of the steel sheet includes mainly polygonal ferrite having a crystal grain size of not more than 4 ?m, and hard microstructures of bainite and martensite, the block size of the martensite is not more than 0.9 ?m, the Cr content within the martensite is 1.1 to 1.5 times the Cr content within the polygonal ferrite, and the tensile strength is at least 880 MPa.

Abstract: A method is proved for hot pressing hot rolled steel sheet, cold rolled steel sheet, Al-based plated steel sheet or Zn-based plated steel sheet, where the hot pressed sheet can exhibit a strength of at least about 1200 Mpa, and my be prevented from exhibiting hydrogen embrittlement. The steel sheet may include between about 0.05 to 0.5 wt % C, and/or it may be plated with an Al-based or Zn-based plating material. The steel sheet may be heating to a temperature greater than an Ac3 temperature and not more than about 1100° C. before pressing. An atmosphere can be provided during heating which contains not more than about 6 vol % of hydrogen and a dew point of not more than about 10° C. The exemplary methods may be used to form high strength parts which may be used, e.g., in automobiles.

Abstract: A high-strength quenched formed body containing a layer on the surface of an after-quenching formed-body steel material in which layer Zn is a major component and which layer contains 30% by mass or less of Fe, and which layer is present in an amount of 30 g/m2 or more. A quenched formed body is produced by quenching a zinc-plated steel material which includes a zinc-plated layer containing each of Al and Si having alloying-retarding function and readily-oxidizing function independently or compositely, in an amount of 0.15% by mass or more, after heating it to 800° C. or more and 950° C. or less in an oxidizing atmosphere containing 0.1% by volume or more of oxygen.

Abstract: A high-strength galvanized steel sheet has a steel composition which contains, by % by mass, 0.01 to 0.12% of C, 0.2% or less of Si, less than 2% of Mn, 0.04% or less of P, 0.02% or less of S, 0.3% or less of sol. Al, 0.01% or less of N, and over 0.3% to 2% of Cr, and which satisfies 2.1?[Mneq]?3 and 0.24?[% Cr]/[% Mn], the balance being composed of iron and inevitable impurities, and has a steel microstructures containing ferrite and a second phase.