Abstract: A method for producing a cold rolled steel sheet having a tensile strength ?1470 MPa and a total elongation TE?19%, the method comprising the steps of annealing at an annealing temperature AT?Ac3 a non-treated steel sheet whose chemical composition contains in weight %: 0.34%?C?0.40%, 1.50%?Mn?2.30%, 1.50?Si?2.40%, 0%<Cr?0.5%, 0%<Mo?0.3%, 0.01%?A1?0.07%, the remainder being Fe and unavoidable impurities, quenching the annealed steel sheet by cooling it to a quenching temperature QT<Ms transformation point and between 150° C. and 250° C., and making a partitioning treatment by reheating the quenched steel sheet to a partitioning temperature PT between 350° C. and 420° C. and maintaining the steel sheet at this temperature during a partitioning time Pt between 15 seconds and 120 seconds.

Abstract: The present disclosure relates to a production of a high-strength steel sheet with excellent combination of strength and ductility, and a method of manufacturing the same. In accordance with a method of manufacturing a high-strength steel sheet, the method may include: heating a steel sheet which can have a residual austenite upon cooling, to form an austenite; primary cooling the austenitized steel sheet to T1 for a bainite region and subjecting to a primary isothermal transformation; and secondary cooling the primary isothermal transformed steel sheet to T2, which is lower than T1 by 50° C. ore more, for a bainite region, and subjecting to a secondary isothermal transformation.

Abstract: The present invention relates to an ultra-high strength, hot-dip galvanized steel sheet having excellent surface quality and coating adherence and to a method for manufacturing thereof, the ultra-high strength, hot-dip galvanized steel sheet comprising: 0.1-0.3% by weight carbon (C); 0.1-2.0% by weight silicon (Si); 0.005-1.5% by weight aluminum (Al); 1.5-3.5% by weight manganese (Mn); 0.04% by weight or less phosphorus (P) (excluding 0% by weight); 0.015% by weight or less sulphur (S) (excluding 0% by weight); 0.02% by weight or less nitrogen (N) (excluding 0% by weight); the balance being Fe; and other inevitable impurities, and further comprising 0.01 wt.% to 0.07 wt.% of at least one kind of element selected from the group consisting of bismuth (Bi), tin (Sn) and antimony (Sb).

Abstract: Disclosed is a high-strength hot-dip galvanized steel sheet produced from a steel sheet containing Si and Mn as a base material and a method for producing the same. The method using the following conditions for a heating process for annealing: (1) The rate of temperature rise when the temperature inside an annealing furnace is in a temperature range of from 450° C. to A° C. inclusive (where A is an arbitrary value selected in a range of 500?A) is 7° C./sec. or more; (2) The maximum steel sheet temperature reached during the annealing is 600° C. or higher and 750° C. or lower; (3) When the temperature of the steel sheet is in a temperature range of from 600° C. to 750° C. inclusive during the annealing, the transit time of the steel sheet is 30 seconds or longer and 10 minutes or shorter, and the dew point of an atmosphere is ?45° C. or lower.

Abstract: Provided is an alloyed hot-dip galvanized steel sheet including a base steel sheet, the base steel sheet containing a given amount of C, Si, Mn, and other elements. The alloyed hot-dip galvanized steel sheet is provided with an alloyed hot-dip galvanized layer on a surface of the base steel sheet, the alloyed hot-dip galvanized layer containing, in mass %, Fe: more than or equal to 5% and less than or equal to 15%, and having a thickness of more than or equal to 3 ?m and less than or equal to 30 ?m.

Abstract: A steel strip is annealed in a vertical annealing furnace including a heating zone and a soaking zone through which the steel strip is vertically conveyed, an atmosphere gas is supplied 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 to form a gas having a lowered dew point that is returned into the furnace. A gas injector having a plurality of gas outlets arranged in a direction of a travel of the steel strip is disposed to suppress a mixing of an atmosphere in the furnace upstream of the gas injector and an atmosphere in the furnace downstream of the gas injector, and a temperature of the steel strip passing through the gas injector is controlled to 600° C. to 700° C.

Abstract: There are provided a method for manufacturing a high manganese hot-dip galvanized steel sheet having superior coatability and ultra-high strength, and a high manganese hot-dip galvanized steel sheet manufactured by the method. The method includes: cold rolling a hot-rolled steel sheet to form a cold-rolled steel sheet, the hot-rolled steel sheet including, by wt %, C: 0.3% to 1%, Mn: 8% to 25%, Si: 0.1% to 3%, Al: 0.01% to 8%, Cr: 0.1% to 2%, Ti: 0.01% to 0.2%, B: 0.0005% to 0.01%, Ni: 0.01% to 2%, Sn: 0.06% to 0.2%, and a balance of Fe and inevitable impurities; heating the cold-rolled steel sheet; cooling the heated steel sheet to, or maintaining the heated steel sheet; and performing a hot-dip galvanizing process on the cooled or temperature-maintained steel sheet by dipping the cooled or temperature-maintained steel sheet into a hot-dip galvanizing bath.

Abstract: The present invention provides a steel sheet with chemical components including, by mass %, 0.18-0.35% of C, 1.0%-3.0% of Mn, 0.01%-1.0% of Si, 0.001%-0.02% of P, 0.0005%-0.01% of S, 0.001%-0.01% of N, 0.01%-1.0% of Al, 0.005%-0.2% of Ti, 0.0002%-0.005% of B, and 0.002%-2.0% of Cr, and the balance of Fe and inevitable impurities, wherein: by volume %, a fraction of the ferrite is 50% or more, and a fraction of a non-recrystallized ferrite is 30% or less; and Cr?/CrM is 2 or less, where Cr? is a concentration of Cr subjected to solid solution in iron carbide and CrM is a concentration of Cr subjected to solid solution in a base material, or Mn0/MnM is 10 or less, where Mn0 is a concentration of Mn subjected to solid solution in an iron carbide, and MnM is a concentration of Mn subjected to solid solution in a base material.

Abstract: A high strength cold rolled steel sheet has a chemical composition including, by mass %, C: 0.06 to 0.13%, Si: 1.2 to 2.3%, Mn: 0.6 to 1.6%, P: not more than 0.10%, S: not more than 0.010%, Al: 0.01 to 0.10% and N: not more than 0.010%, the balance comprising Fe and inevitable impurities. The steel sheet includes a microstructure containing not less than 90% in terms of volume fraction of ferrite with an average grain diameter of less than 20 ?m and 1.0 to 10% in terms of volume fraction of pearlite with an average grain diameter of less than 5 ?m. The ferrite has an average Vickers hardness of not less than 130. The steel sheet has a yield ratio of not less than 65% and a tensile strength of not less than 590 MPa.

Abstract: A cold rolled steel sheet according to the present invention satisfies an expression of (5×[Si]+[Mn])/[C]>11 when [C] represents an amount of C by mass %, [Si] represents an amount of Si by mass %, and [Mn] represents an amount of Mn by mass %, a metallographic structure before hot stamping includes 40% to 90% of a ferrite and 10% to 60% of a martensite in an area fraction, a total of an area fraction of the ferrite and an area fraction of the martensite is 60% or more, a hardness of the martensite measured with a nanoindenter satisfies an H2/H1<1.10 and ?HM<20 before the hot stamping, and TS×? which is a product of a tensile strength TS and a hole expansion ratio ? is 50000 MPa·% or more.

Abstract: High strength steel sheet and high strength galvanized steel sheet which are excellent in shapeability which secure a tensile maximum strength 900 MPa or more high strength while obtaining excellent ductility and stretch flangeability, which sheets have predetermined compositions of ingredients, have steel sheet structures which contain volume fraction 1 to 20% of residual austenite phases, and which have martensite transformation points of the residual austenite phases of ?60° C. or less.

Abstract: Provided is a galvannealed steel sheet with excellent anti-powdering property when press forming is performed, without controlling the contents of chemical elements in steel which are effective for strengthening a steel sheet, such as Si and P, to be low in order to achieve required material properties and without increasing cost due to, for example, processes being complicated. A galvannealed steel sheet with excellent anti-powdering property has a coated layer taking in grains of a base steel sheet such that the grains constitute 2.0% or more and 15.0% or less of the coated layer in terms of cross section area ratio.

Abstract: A coated dual-phase steel and process for producing the coated dual-phase steel is provided. The process includes providing a steel slab with a desired chemistry, soaking the slab at an elevated temperature and then hot rolling the slab to produce hot-rolled strip. The hot-rolled strip is coiled and has a ferrite-pearlite microstructure. The coiled hot-rolled strip is cold-rolled into cold-rolled sheet with at least a 60% reduction in thickness compared to the thickness of the coiled hot-rolled strip. The cold-rolled sheet is subjected to an intercritical anneal followed by rapid cooling with the absence of an isothermal heat treatment or hold after rapid cooling near the molten metal pot temperature—during which, before or after which the steel is coated. The coated steel sheet has a dual-phase ferrite-martensite microstructure, a yield strength of at least 310 MPa, a tensile strength of at least 580 MPa and a total elongation to failure of at least 18%.

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 a base steel sheet, the hot-dip galvanized steel sheet having excellent elongation properties and being characterized by the composition and the microstructure thereof.

Abstract: High strength steel sheet which secures tensile maximum strength 900 MPa or more high strength while having excellent shapeability, which high strength steel sheet which is excellent in shapeability characterized by having a predetermined composition of ingredients, by the steel sheet structure including a ferrite phase and martensite phase, by the ratio of Cu particles incoherent with the bcc iron being 15% or more with respect to the Cu particles as a whole, by a density of Cu particles in the ferrite phase being 1.0×1018/m3 or more, and by an average particle size of Cu particles in the ferrite phase being 2.0 nm or more.

Abstract: The present invention provides a method for manufacturing a hot stamped body, the method including: a hot-rolling step; a coiling step; a cold-rolling step; a continuous annealing step; and a hot stamping step, in which the continuous annealing step includes a heating step of heating the cold-rolled steel sheet to a temperature range of equal to or higher than Ac1° C. and lower than Ac3° C.; a cooling step of cooling the heated cold-rolled steel sheet from the highest heating temperature to 660° C. at a cooling rate of equal to or less than 10° C./s; and a holding step of holding the cooled cold-rolled steel sheet in a temperature range of 550° C. to 660° C. for one minute to 10 minutes.

Abstract: A high-strength hot-dip galvanized steel sheet containing a main component, the steel sheet having at least 40 wt. % of ferrite as a main phase in terms of the volumetric ratio, and 8-60% inclusive of residual austenite, the remaining structure comprising one or more of bainite, martensite, or pearlite. Austenite particles within a range where the average residual stress (sigmaR) thereof satisfies the expression ?400 MPa<=sigmaR<=200 MPa (formula (1)) are present in an amount of 50% or more in the hot-dip galvanized steel sheet. The surface of the steel sheet has a hot-dip galvanized layer containing less than 7 wt. % of Fe, the remainder comprising Zn, Al and inevitable impurities.

Abstract: A hot dip galvanized steel sheet includes a steel sheet, a hot dip galvanizing layer, and an intermetallic compound, in which the steel sheet has a chemical composition containing, by mass %, C: 0.03% or more and 0.70% or less, Si: 0.10% or less, Mn: 0.5% or more and 0.9% or less, P: 0.020% or more and 0.050% or less, S: 0.010% or less, Nb: 0.010% or more and 0.035% or less, N: 0.005% or less, Al: 0.10% or less, and the balance being Fe and inevitable impurities, in which the hot dip galvanizing layer contains 0.3% or more and 0.6% or less of Al, and in which the intermetallic compound contains 0.12 gm?2 or more and 0.22 gm?2 or less of Al and Fe2Al5 having an average grain diameter of 1 ?m or less.

Abstract: Exemplary embodiments of the present invention can provide a hot dip galvannealed steel sheet which has excellent corrosion resistance, workability, coatability and appearance. The exemplary galvannealed sheet can include an ultra-low carbon steel sheet having a plating layer which includes about 8 to 13% Fe, about 0.05 to 1.0% Ni, about 0.15 to 1.5% Al, and a balance of Zn and unavoidable impurities. An exemplary method for producing a hot dip galvannealed steel sheet is also provided which can include cleaning an annealed ultra-low carbon steel sheet, preplating it with Ni, rapidly heating the sheet in a nonoxidizing or reducing atmosphere, plating the sheet in a galvanization bath containing Al, wiping it, then rapidly reheating it and either cooling the sheet without any soaking time or soaking and holding it for less than 15 seconds and then cooling it.

Abstract: There is provided a high-strength galvanized steel sheet including, on a mass percent basis, C: more than 0.060% and 0.13% or less, Si: 0.01% or more and 0.7% or less, Mn: 1.0% or more and 3.0% or less, P: 0.005% or more and 0.100% or less, S: 0.010% or less, sol.Al: 0.005% or more and 0.100% or less, N: 0.0100% or less, Nb: 0.005% or more and 0.10% or less, Ti: 0.03% or more and 0.15% or less, and the balance comprising Fe and incidental impurities, satisfying the relationship of (Nb/93+Ti*/48)/(C/12)>0.08 (wherein Ti*=Ti?(48/14)N?(48/32)S). The high-strength galvanized steel sheet has a structure including ferrite and martensite. The ferrite has an average grain diameter of 15 ?m or less and an area percentage of 80% or more. The martensite has an area percentage of 1% or more and 15% or less.

Abstract: A galvanized steel sheet has a composition containing, by mass %, C: 0.05% or more and 0.5% or less, Si: 0.01% or more and 2.5% or less, Mn: 0.5% or more and 3.5% or less, P: 0.003% or more and 0.100% or less, S: 0.02% or less, Al: 0.010% or more and 0.5% or less, B: 0.0002% or more and 0.005% or less, Ti: 0.05% or less, a relationship of Ti>4N being satisfied, and the balance comprising Fe and inevitable impurities, and a microstructure containing 60% or more and 95% or less of tempered martensite in terms of area ratio and 5% or more and 20% or less of retained austenite in terms of area ratio.

Abstract: The invention provides a cold-rolled steel sheet excellent in paint bake hardenability and ordinary-temperature non-aging property comprising, in mass %, C: 0.0005-0.0040%, Si: 0.8% or less, Mn: 2.2% or less, S: 0.0005-0.009%, Cr: 0.4-1.3%, O: 0.003-0.020%, P: 0.045-0.12%, B: 0.0002-0.0010%, Al: 0.008% or less, N: 0.001-0.007%, and a balance of Fe and unavoidable impurities. Ultra-low-carbon steel retaining solute N and containing added Cr, P, B and O is used to produce hot-rolled and cold-rolled steel sheet and hot-dip galvanized cold-rolled steel sheet that exhibit both high paint bake hardenability and ordinary-temperature non-aging property.

Abstract: A readily formable flat steel product has a ductile edge layer that is from 10 to 200 ?m thick and has a ductility greater than a ductility of an inner core layer of the flat steel product. The readily formable flat steel product is produced by annealing a flat steel product having a C content of from 0.1 to 0.4% by weight in a continuous furnace. The annealing is carried out under an annealing atmosphere that contains from 0.1 to 25% by vol. of H2 and H2O, with the balance being N2 and technically unavoidable impurities. A dew point is between ?20° C. and +60° C., and a ratio of H2O/H2 is a maximum of 0.957. In the course of the annealing, the flat steel product is heated to a holding temperature of from 600 to 1100° C. and for a holding time of from 10 to 360 seconds.

Abstract: A high-strength alloyed hot-dip galvanized steel sheet obtained by subjecting the surface of a high-strength steel sheet to alloyed hot-dip galvanization, and formed from a steel sheet containing, in mass %, main components, and containing at least 40 vol % bainite and/or martensite, 8-60 vol % retained austenite, and less than 40 vol % ferrite, with the remainder comprising unavoidable structures. In the alloyed hot-dip galvanized steel sheet, the total thickness of the Gamma1 layer and the Gamma layer (Tgamma1+Tgamma) is 2 ?m or less in the alloy layers formed by hot-dip galvanization, and the Gamma1 phase/Gamma phase thickness ratio (Tgamma1/Tgamma) is 1 or less. A tensile strength of 980 MPa or above can be easily imparted to the alloyed hot-dip galvanized steel sheet. The alloyed hot-dip galvanized steel sheet has excellent coating adherence, and coating separation during machining can be suppressed.

Abstract: A high strength hot-dip galvanized steel sheet has TS of 440 MPa or more and an average r value of 1.30 or more, where the absolute value of the planar anisotropy of the r value (?r) is 0.20 or less. A chemical composition contains C: 0.010% or more and 0.04% or less, Si: more than 1.0% and 1.5% or less, Mn: 1.0% or more and 3.0% or less, P: 0.005% or more and 0.1% or less, S: 0.01% or less, sol. Al: 0.005% or more and 0.5% or less, N: 0.01% or less, Nb: 0.010% or more and less than 0.05%, Ti: 0.015% or more and 0.120% or less, and the remainder composed of Fe and incidental impurities, wherein (Nb/93)/(C/12) 0.20 and 0.005<C*?0.020 are satisfied.

Abstract: An annealing and manufacturing method of hot-dip galvanized steel strips includes suppression of oxide formation of elements in the steel strips. An annealing furnace includes a heating zone, a soaking zone, and a cooling zone in which a portion of gas is introduced to decrease the gas dew point. A gas suction rate Qo1 in a portion of the cooling zone, a gas suction rate Qo2 in an upper portion and a gas feed rate Qi2 in a lower portion of the soaking zone, a gas feed rate Qi1 in a connection part between the soaking and cooling zones, an atmosphere gas supply rate Qf1 into the cooling zone and its subsequent zone, an atmosphere gas supply rate Qf2 into the soaking zone, an internal volume Vs of the soaking zone, and an average furnace temperature Ts of the soaking zone satisfy relationships including 0.3×Qf1<Qo1.

Abstract: A high-strength alloyed hot-dip galvanized steel sheet obtained by subjecting the surface of a high-strength steel sheet to alloyed hot-dip galvanization, and formed from a steel sheet containing, in mass %, main components, and containing at least 40 vol % bainite and/or martensite, 8-60 vol % retained austenite, and less than 40 vol % ferrite, with the remainder comprising unavoidable structures. In the alloyed hot-dip galvanized steel sheet, the total thickness of the Gamma1 layer and the Gamma layer (Tgamma1+Tgamma) is 2 ?m or less in the alloy layers formed by hot-dip galvanization, and the Gamma1 phase/Gamma phase thickness ratio (Tgamma1/Tgamma) is 1 or less. A tensile strength of 980 MPa or above can be easily imparted to the alloyed hot-dip galvanized steel sheet. The alloyed hot-dip galvanized steel sheet has excellent coating adherence, and coating separation during machining can be suppressed.

Abstract: A method for manufacturing a coated part having very high mechanical properties using hot forming techniques. The method includes: —providing an annealed steel strip or blank or pre-shaped part that was coated with a metal or metal alloy before the annealing —if a strip is provided, cutting a blank from the strip before or after the annealing —optionally forming a pre-shaped part from the blank —heating the blank or preshaped part to a temperature of 500° C. at an average heating rate of 16° C./s or more —further heating the blank or pre-shaped part to a temperature between 700 and 1000° C. —hot forming the blank or preshaped part into a hot formed part —hardening the hot formed part. A method for manufacturing a coated steel strip, blank or pre-shaped part, and a coated steel strip, blank or part and a hot formed part.

Abstract: Exemplary embodiments of a facility or an arrangement capable of producing a high strength steel sheet or a hot dip zinc coated high strength steel sheet according to the present invention are provided which can make a quenching facility and tempering facility continuous treatment facilities. For example, an improvement in the material quality can be effectuated due to tempering enable improvement of the hole expandability. In addition, an elongation of the sheet can be improved.

Abstract: A strain aging hardening type steel sheet excellent in aging resistance, and manufacturing method thereof, said steel sheet comprises: in mass %, C: 0.0010 to 0.010%; Si: 0.005 to 1.0%; Mn: 0.08 to 1.0%; P: 0.003 to 0.10%; S: 0.0005 to 0.020%; Al: 0.010 to 0.10%; Cr: 0.005 to 0.20%; Mo: 0.005 to 0.20%; Ti: 0.002 to 0.10%; Nb: 0.002 to 0.10%; N: 0.001 to 0.005%; and a balance being composed of Fe and inevitable impurities, in which a ferrite fraction is 98% or more, an average grain diameter of ferrite is 5 to 30 ?m, a minimum value of dislocation density in a portion having a ½ thickness of a sheet thickness and a minimum value of dislocation density in a surface layer portion are each 5×1012/m2 or more, and an average dislocation density falls within a range of 5×1012 to 1×1015/m2.

Abstract: A high strength galvanized steel sheet includes a steel sheet which is a base sheet and a galvanized layer on a surface of the steel sheet, the steel sheet has a composition including, by mass %, 0.08 to 0.15% of C, 0.5 to 1.5% of Si, 0.5 to 1.5% of Mn, 0.1% or less of P, 0.01% or less of S, 0.01 to 0.1% of Al, 0.005% or less of N, and the balance Fe with inevitable impurities, and a microstructure composed of 75 to 90% of a ferrite phase as a main phase and 10 to 25% of a second phase including at least pearlite in terms of an area fraction with respect to the entire microstructure; an average grain size of the pearlite is 5 ?m or smaller; and the pearlite has an area fraction of 70% or greater with respect to the total area of the second phase.

Abstract: A rolled steel sheet or blank is provided, the composition of which comprises the elements listed below in per cent by weight: C?0.1%; 0.5%?Mn?7%; 0.5%?Si?3.5%; 0.5%<Ti?2%; 2%<Ni?7%; Al?0.10%; Cr?2%; Cu?2%; Co?2%; Mo?2%; S?0.005%; P?0.03%; Nb?0.1%; V?0.1%; B<0.005%; N?0.008%, and the silicon and titanium contents are such that: Si + Ti ? 2.5 ? % , Ti Si ? 0.3 the remainder of the composition consisting of iron and unavoidable impurities resulting from processing. A method for the fabrication of a part for a land motor vehicle from the sheet or blank by hot stamping is also provided. The microstructure of the part consisting essentially of martensite and intermetallic precipitates of type Fe2TiSi with an area percentage between 1 and 5% intermetallic precipitates.

Abstract: A method of manufacturing a high-strength galvanized steel sheet includes hot-rolling a slab to form a steel sheet; during continuous annealing, heating the steel sheet to a temperature of 750° C. to 900° C. at an average heating rate of at least 10° C./s at a temperature of 500° C. to an A1 transformation point; holding that temperature for at least 10 seconds; cooling the steel sheet from 750° C. to a temperature of (Ms point—100° C.) to (Ms point—200° C.) at an average cooling rate of at least 10° C./s; reheating the steel sheet to a temperature of 350° C. to 600° C.; holding that temperature for 10 to 600 seconds; and galvanizing the steel sheet.

Abstract: Provided is a method for producing a plated steel sheet with high Si content for hot stamping, which is capable of suppressing the generation of unplated portions, while maintaining high bonding strength in a welded part in cases where a galvanized steel sheet containing a large amount of Si, namely, 0.7% or more of Si is used for hot stamping applications. In this production method, a hot-rolled pickled steel sheet or cold-rolled steel sheet containing 0.10-0.5% by mass of C, 0.7-2.5% by mass of Si, 1.0-3% by mass of Mn, and 0.01-0.5% by mass of Al is annealed in a reducing atmosphere and then plated, thereby producing a galvanized steel sheet for hot stamping. This method for producing a galvanized steel sheet for hot stamping is characterized in that the annealing is carried out within the range of 500 to 700° C. for 30 to 270 seconds.

Abstract: Provided are: a high-strength hot-dip galvanized steel sheet in which bending workability of the high-strength hot-dip galvanized steel sheet is improved, and in which strength difference between a center part and end parts in the sheet width direction is reduced; and a method for manufacturing a high-strength hot-dip galvanized steel sheet. The steel sheet is a hot-dip galvanized steel sheet having a hot-dip galvanizing layer on a surface of a base steel sheet containing: C, Mn, P, S, and Al; Ti and B in amounts satisfying equation (1); and N; and Si as needed; the remainder comprising iron and unavoidable impurities; the metallographic structure of the base steel sheet having martensite, bainite, and ferrite, the ratios of each with respect to the overall metallographic structure being 50 area % or more of the martensite, 15-50 area % of the bainite, and 5 area % or less of the ferrite, 0.005×[Mn]+0.02×[B]1/2+0.025?[Ti]?0.15.

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: Provided is a method that enables manufacture, with good productivity, of a high-strength cold-rolled steel with improved elongation (EL), stretch-flangeability (?), bendability (R), and balance of these properties (TS×EL×?/1000), outstanding composite workability as evaluated by Erichsen test, and a tensile strength of at least 980 MPa. A steel material satisfying a prescribed constituent composition is held and soaked for at least fifty seconds at a temperature at or above the Ac3 point, after which the steel material is cooled at an average cooling rate of at least 15° C./sec to a discretionary temperature (T) that satisfies expression (1) below, held for 5-180 seconds in a temperature range that satisfies expression (1) below, then heated to a temperature region that satisfies expression (2) below, held for at least 50 seconds in this temperature region, and then cooled. 300° C.?T1 (° C.)<400° C. ??(1) 400° C.?T2 (° C.)<540° C.

Abstract: A galvanized steel sheet includes a zinc plating layer which is disposed on a steel sheet containing 0.01% to 0.15% C, 0.001% to 2.0% Si, 0.1% 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, and which has a mass per unit area 20 g/m2 to 120 g/m2. An oxide of at least one selected from the group consisting of Fe, Si, Mn, Al, and P is present in a surface portion of the steel sheet that lies directly under the zinc plating layer and that extends up to 100 ?m from the surface of a base steel sheet. The amount of the oxide per unit area is 0.05 g/m2 or less in total. The steel sheet has excellent corrosion resistance, anti-powdering property during heavy machining, and strength.

Abstract: A high-strength cold-rolled steel sheet has a specific chemical composition and has a steel microstructure meeting conditions: a total content of bainitic ferrite (BF) and tempered martensite (TM) is 65% (in area percent, hereinafter the same for steel microstructure) or more; a fresh martensite (M) content is 3% to 18%; a retained austenite content is 5% or more; and a polygonal ferrite (F) content is 5% or less. The steel sheet has a specific average KAM<1.00° of 0.50° or more and has a tensile strength of 980 MPa or more. The high-strength cold-rolled steel sheet excels in formability and shape fixability.

Abstract: The steel for hot forming has the following composition in weight %: C: 0.10-0.25, Mn: 1.4-2.8, Si: ?1.0, Cr: ?1.0, Ti: ?0.05, Nb: ?0.05, V: ?0.1, Mo: ?0.1, Al: ?0.05, P: ?0.02, S: ?0.005, Ca: ?0.005, O: ?0.01, N: ?0.02, B: ?0.0004, the remainder being iron and unavoidable impurities. Also disclosed is a strip, sheet or blank produced with such a steel, a method for producing a hot formed product, such a product and the use thereof.

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: The high strength steel sheet has a chemical composition including 0.08% to 0.20% of C, 0.3% or less of Si, 0.1% to 3.0% of Mn, 0.10% or less of P, 0.030% or less of S, 0.10% or less of Al, 0.010% or less of N, 0.20% to 0.80% of V, and the remainder composed of Fe and incidental impurities on a percent by mass basis, and a microstructure which includes 95% or more of ferrite phase on an area percentage basis, in which fine precipitates are dispersed having a distribution in such a way that the number density of precipitates having a particle size of less than 10 nm is 1.0×105/?m3 or more and the standard deviation of natural logarithm values of precipitate particle sizes with respect to precipitates having a particle size of less than 10 nm is 1.5 or less.

Abstract: The invention relates to a method for producing a component from transformable steel by hot forming, in which a plate first is cut out of a strip or sheet as the pre-material, and is then heated to forming temperature and pre-formed, having an at least partially martensitic transformation structure after forming. Instead of a press mould hardening, the at least partially martensitic transformation structure is created in the pre-material, or in the plate to be formed, by austenitisation and quenching already before forming, and then the thus-conditioned plate is reheated after forming, while maintaining the at least partially martensitic transformation structure, to a temperature below the Ac1 transformation temperature, and formed at this temperature.

Abstract: A method for manufacturing a high strength galvanized steel sheet and a high strength galvanized steel sheet are provided. A base steel sheet having a chemical composition comprising C: 0.03% to 0.35%, Si: 0.01% to 0.50%, Mn: 3.6% to 8.0%, Al: 0.001% to 1.000%, P?0.10%, S?0.010%, and the balance comprising Fe and incidental impurities, on a percent by mass basis, is subjected to annealing and galvanization treatment, wherein the maximum steel sheet temperature in an annealing furnace is 600° C. or higher and 700° C. or lower, the steel sheet transit time in a temperature region of the maximum steel sheet temperature of 600° C. or higher and 700° C. or lower is specified to be 30 seconds or more and 10 minutes or less, and the dew point in an atmosphere is specified to be ?45° C. or lower.

Abstract: A high strength hot dip galvanized steel strip including, in mass percent, of the following elements: 0.10-0.18% C, 1.90-2.50% Mn, 0.30-0.50% Si, 0.50-0.70% Al, 0.10-0.50% Cr, 0.001-0.10% P, 0.01-0.05% Nb, max 0.004% Ca, max 0.05% S, max 0.007% N, and optionally at least one of the following elements: 0.005-0.50% Ti, 0.005-0.50% V, 0.005-0.50% Mo, 0.005-0.50% Ni, 0.005-0.50% Cu, max 0.005% B, the balance Fe and inevitable impurities, wherein 0.80%<Al+Si<1.05% and Mn+Cr>2.10%. This steel offers improved formability at a high strength, has a good weldability and surface quality together with a good produce-ability and coat-ability.

Abstract: Disclosed is a hot-dip galvanized steel sheet for stamping, which has excellent cold workability, has such satisfactory surface quality as to be free from unplating and other defects even in the absence of dedicated facilities, and ensures a strength of 1370 MPa or more after quenching even when cooled at a low rate. Also disclosed is a method effective for the produce of the hot-dip galvanized steel sheet for stamping. The hot-dip galvanized steel sheet for stamping comprises a base steel sheet and a hot-dip galvanized layer on a surface of the base steel sheet, in which the base steel sheet has a predetermined chemical composition and has a microstructure comprising equiaxed ferrite having an average aspect ratio of 4.0 or less and cementite and/or pearlite having an average major axis of grains of 20 ?m or less.

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: A method for manufacturing a high strength galvanized steel sheet and a high strength galvanized steel sheet are provided. A high strength galvanized steel sheet having a zinc coating layer with an amount of deposition of coating of 20 to 120 g/m2 per one surface on the surface of a base steel sheet having a chemical composition comprising C: 0.03% to 0.35%, Si: 0.01% to 0.50%, Mn: 3.6% to 8.0%, Al: 0.001% to 1.000%, P?0.10%, S?0.010%, and the balance comprising Fe and incidental impurities, on a percent by mass basis, is produced. At this time, in annealing and galvanization treatment of the base steel sheet in a continuous galvanizing line, the maximum steel sheet temperature in an annealing furnace is 600° C. or higher and 750° C. or lower, the steel sheet transit time in a temperature region of the maximum steel sheet temperature of 600° C. or higher and 750° C. or lower is specified to be 30 seconds or more and 10 minutes or less, and the dew point in an atmosphere is specified to be ?10° C. or higher.

Abstract: The present invention provides a high-strength hot-rolled steel sheet having both excellent strength and excellent workability (particularly, bending workability), and a method of producing the same. The steel sheet of the present invention has a certain composition as well as microstructures such that an area ratio of ferrite phase is 95% or more, an average grain size of the ferrite phase is 8 ?m or less, and carbides in grains of the ferrite phase have an average particle size of less than 10 nm. The steel sheet of the present invention also has a tensile strength of 980 MPa or more.

Abstract: The invention provides a steel sheet for hot press-forming that can reliably give hot press-formed parts having excellent paint adhesiveness, perforation corrosion resistance and joint corrosion resistance, and also provides a method for manufacturing the steel sheet for hot press-forming, and a method for producing hot press-formed parts using the steel sheet for hot press-forming. The steel sheet for hot press-forming includes a base steel sheet and a Zn-based coating layer with a mass of coating of 10 to 90 g/m2 on the base steel sheet, wherein the average ferrite grain diameter in the surface microstructure of the base steel sheet is not more than 20 ?m.