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: The invention relates to a method for producing packaging steel consisting of a cold-rolled steel sheet made of unalloyed or low-alloy steel having a carbon content of less than 0.1%. In order to provide high-strength packaging steel that has good formability and high corrosion resistance and can be produced in as energy-saving a manner as possible, the steel sheet according to the invention is first coated with a metallic coating and then annealed in a recrystallising manner at a heating rate of more than 75 K/s and preferably more than 100 K/s to temperatures of more than 700° C., such that the metallic coating melts. The coated and annealed steel sheet is then quenched to normal temperature at a cooling rate of at least 100 K/s.

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

Abstract: A high-manganese hot-rolled galvanized steel sheet having no surface defects and improved galvanizing and alloying characteristics is manufactured by using a high-manganese hot-rolled steel sheet. Provided are the high-manganese hot-rolled galvanized steel sheet and a method of manufacturing the high-manganese hot-rolled galvanized steel sheet. The high-manganese hot-rolled galvanized steel sheet includes: a hot-rolled steel sheet including 5 wt % to 35 wt % manganese; and a zinc coating layer formed on the hot-rolled steel sheet, wherein an internal oxide layer is formed in an internal region of the hot-rolled steel sheet facing the zinc coating layer.

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, or further containing 10% or less (including 0%) of ferrite in terms of area ratio and/or 10% or less (including 0%) of martensite in terms of area ratio, the tempered martensite having an average grain diameter of 5 ?m or less.

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

Abstract: A low density high strength steel sheet including 0.15% to 0.25% C, 2.5% to 4% Mn, 0.02% or less P, 0.015% or less S, 6% to 9% Al and 0.01% or less N, the balance being iron and inevitable impurities, wherein 1.7·(Mn—Al)+52.7·C is at least 3 and at most 4.5. A method of producing the low density and high strength steel sheet.

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, a steel sheet microstructure includes 80% or more of ferrite and 3% or more of martensite on an area ratio basis, and C*=C-(12/93)Nb-(12/48){Ti-(48/14)N-(48/32)S}.

Abstract: A method of manufacturing a high strength steel sheet having excellent formability suitable for the material of an automotive part has a tensile strength (TS) of 980 MPa or more and total elongation (EL) is 25% or more. A steel slab has a chemical composition containing C: 0.03% to 0.35%, Si: 0.5% to 3.0%, Mn: 3.5% to 10.0%, P: 0.100% or less, S: 0.02% or less, and the remainder includes Fe and incidental impurities on a percent by mass basis is hot-rolled, a heat treatment is performed, in which an achieved temperature of Ac1 to Ac1+100° C. is held for 3 minutes or more, subsequently, cold rolling is performed at a rolling reduction of 20% or more and, annealing is performed, in which an achieved temperature of Ac1?30° C. to Ac1+100° C. is held for 1 minute or more.

Abstract: A cold-rolled steel sheet includes, by mass %: C: 0.020% or more and 0.080% or less, Si: 0.20% or more and 1.00% or less; Mn: 0.80% or more and 2.30% or less: and Al: 0.010% or more and 0.100% or less; and further includes: one or more of Nb and Ti which satisfy a requirement of 0.005%?Nb+Ti<0.030%, in which a structure consists of, ferrite, bainite, and other phases, an area ratio of the ferrite is 80% or more and less than 95%, an area ratio of a non-recrystallization ferrite in the ferrite is 1% or more and less than 10%, an area ratio of the bainite is 5% or more and 20% or less, a total amount of the other phases is less than 8%, an equivalent circle diameter of a carbonitride including one or both of Nb and Ti is 1 nm or more and 10 nm or less, and a tensile strength is 590 MPa or more.

Abstract: Provided is a hot-dip galvanized steel sheet having excellent adhesiveness at ultra-low temperatures as well as fine spangles, and a method of manufacturing the same. According to the present invention, a hot-dip galvanized steel sheet having excellent adhesiveness at ultra-low temperatures includes a base steel sheet, a composite layer formed on the base steel sheet and including transition metal, an inhibition layer formed on the composite layer and including a iron-aluminum (Fe—Al) based intermetallic compound, and a zinc (Zn)-plated layer formed on the inhibition layer, in which an average diameter of spangles in the zinc-plated layer is 150 ?m or less, and a method of manufacturing the hot-dip galvanized steel sheet is provided.

Abstract: A system for hot-forming blanks (P) includes at least one heating device (4) and at least one pressing device (8) arranged downstream of the at least one heating device (4), and at Least one reheating device (16) for at least partially acting upon the blanks formed in the pressing device with heat provided downstream of the pressing device (2). A method is also provided.

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

Abstract: Steel with high strength and good formability is produced with compositions and methods for forming austenitic and martensitic microstructure in the steel. Carbon, manganese, molybdenum, nickel copper and chromium may promote the formation of room temperature stable (or meta-stable) austenite by mechanisms such as lowering transformation temperatures for non-martensitic constituents, and/or increasing the hardenability of steel. Thermal cycles utilizing a rapid cooling below a martensite start temperature followed by reheating may promote formation of room temperature stable austenite by permitting diffusion of carbon into austenite from martensite.

Abstract: Steel with high strength and good formability is produced with compositions and methods for forming austenitic and martensitic microstructure in the steel. Carbon, manganese, molybdenum, nickel copper and chromium may promote the formation of room temperature stable (or meta-stable) austenite by mechanisms such as lowering transformation temperatures for non-martensitic constituents, and/or increasing the hardenability of steel. Thermal cycles utilizing a rapid cooling below a martensite start temperature followed by reheating may promote formation of room temperature stable austenite by permitting diffusion of carbon into austenite from martensite.

Abstract: A zinc-coated steel may be produced by performing a pre-alloying heat treatment after galvannealing the steel and prior to the hot stamping the steel. The pre-alloying heat treatment is conducted at a temperature between about 850° F. and about 950° F. in an open coil annealing process. The pre-alloying heat treatment allows for shorter time at the austenitization temperature to form a desired ?-Fe phase in the coating by increasing the concentration of iron. This also decreases the loss of zinc, and a more adherent oxide exists after hot stamping.

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

Abstract: A formable galvanized steel sheet includes, in terms of % by mass, 0.05 to 0.3% of C, 0.01 to 2.5% of Si, 0.5 to 3.5% of Mn, 0.003 to 0.100% of P, 0.02% or less of S, 0.010 to 1.5% of Al, and 0.01 to 0.2% in total of at least one element selected from Ti, Nb and V, the remainder being Fe and unavoidable impurities, having a microstructure composed of, in terms of area fraction, 20 to 87% of ferrite, 3 to 10% in total of martensite and residual austenite, and 10 to 60% of tempered martensite, and a second phase composed of the martensite, residual austenite, and tempered martensite having an average crystal grain diameter of 3 ?m or less, and having a ratio of absorption energy AE to tensile strength TS (AE/TS) not less than 0.063.

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: A method for annealing a strip of steel having a variable thickness in its length direction with at least thicker and thinner sections, wherein the strip has been cold rolled to form the thicker and thinner sections, one thicker and one thinner section having a length of at most a few meter. The annealing is performed by continuous annealing.

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: A bake hardenable steel and a process for manufacture of a bake hardenable steel. Steel alloy slabs with a predefined chemical composition are hot rolled into hot rolled strip. The hot rolled strip is cold rolled and continuously annealed on a continuous annealing line and then rapidly cooled to at least 600° C. using a cooling rate of between 20-100 K/sec, and optionally cooled to at least 140° C. using a cooling rate of between 3-20 K/sec. As such, the cold rolled and annealed sheet is not subjected to an overageing treatment and yet still exhibits excellent and well defined bake hardening values. For example BH2 values between 25 and 45 MPa are exhibited by the low alloy steel grades. In addition, the bake hardeneable steel sheet has a minimum yield strength of 220 MPa and in some instances has a minimum yield strength as high as 380 MPa.

Abstract: The present invention provides a high-strength steel sheet excellent in shape fixability. The high-strength steel sheet contains C, Si, Mn, P, S, Al, N, and O with predetermined contents, in which a retained austenite phase of 5 to 20% in volume fraction is contained, an amount of solid-solution C contained in the retained austenite phase is 0.80 to 1.00% in mass %, WSi? is 1.10 times or more WSi*, WMn? is 1.10 times or more WMn*, and when a frequency distribution is measured with respect to a sum of a ratio between WSi and WSi* and a ratio between WAl and WAl*, a mode value of the frequency distribution is 1.95 to 2.05, and a kurtosis is 2.00 or more.

Abstract: A high strength pressed member has excellent ductility and stretch flangeability and tensile strength of 780-1400 MPa, with a predetermined steel composition and steel microstructure relative to the entire microstructure of steel sheet, where area ratio of martensite 5-70%, area ratio of retained austenite 5-40%, area ratio of bainitic ferrite in upper bainite 5% or more, and total thereof is 40% or more, 25% or more of martensite is tempered martensite, polygonal ferrite area ratio is above 10% and below 50% to the entire microstructure of steel sheet, and average grain size is 8 ?m or less, average diameter of a group of polygonal ferrite grains is 15 ?m or less, the group of polygonal ferrite grains represented by a group of ferrite grains of adjacent polygonal ferrite grains, and average carbon content in retained austenite is 0.70 mass % or more and tensile strength is 780 MPa or more.

Abstract: A high-strength hot-dip galvanized steel sheet has excellent workability, namely, excellent ductility and hole expansion formability, and high yield ratio. The steel sheet has a chemical composition containing by mass %: C: 0.05-0.15%; Si: 0.10-0.90%; Mn: 1.0-1.9%; P: 0.005-0.10%; S: 0.0050% or less; Al: 0.01-0.10%; N: 0.0050% or less; Nb: 0.010-0.100%; and the balance being Fe and incidental impurities, in which: the steel sheet has a complex phase that includes: ferrite having an average crystal grain size of 15 ?m or less to at least 90% in volume fraction; martensite having an average crystal grain size of 3.0 ?m or less to 0.5% or more and less than 5.0% in volume fraction; pearlite to 5.0% or less in volume fraction; and the balance being a phase generated at low temperature.

Abstract: A method for manufacturing the high strength steel sheet having excellent formability includes hot-rolling a steel slab having a chemical composition containing, by mass %, C: 0.03% or more and 0.35% or less, Si: 0.5% or more and 3.0% or less, Mn: 3.5% or more and 10.0% or less, P: 0.1% or less, S: 0.01% or less, N: 0.008% or less and the balance comprising Fe and inevitable impurities, coiling the hot-rolled steel sheet at a temperature range of the Ar1 transformation point to the Ar1 transformation point+(the Ar3 transformation point?the Ar1 transformation point)/2, cooling the coiled steel sheet down to 200° C. or lower, heating and holding the cooled steel sheet at a temperature range of the Ac1 transformation point?200° C.

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: The invention relates to a steel part, the composition of the steel of which comprises, the contents being expressed by weight: 0.040%?C?0.100%; 0.80%?Mn?2.00%; Si?0.30%; S?0.005%; P?0.030%; 0.010%?Al?0.070%; 0.015%?Nb?0.100%; 0.030%?Ti?0.080%; N?0.009%; Cu?0.100%; Ni?0.100%; Cr?0.100%; Mo?0.100%; and Ca?0.006%, the balance of the composition consisting of iron and inevitable impurities resulting from the smelting, the microstructure of the steel consisting of at least 75% equiaxed ferrite, martensite in an amount not less than 5% but not exceeding 20%, and bainite in an amount not exceeding 10%.

Abstract: Provided are a high-strength hot-dip galvanized steel sheet having excellent formability and a tensile strength of 440 MPa or more and a method for manufacturing the same. A steel sheet has a microstructure containing a ferrite phase having an area fraction of 60% or more, a pearlite phase having an area fraction of 20% to 30%, and a bainite phase having an area fraction of 1% to 5%, the area fraction of a cementite phase present in a grain of the ferrite phase being 5% or less. Upon manufacture, a hot-rolled sheet or a cold-rolled sheet is heated to a temperature of 650° C. or higher at an average heating rate of 10° C./s or more, is held at a temperature of 700° C. to (Ac3-5)° C. for ten seconds or more, is cooled to a temperature of 300° C. to 500° C. at an average cooling rate of 10° C./s to 200° C./s, is held at a temperature of 300° C. to 500° C. for 30 seconds to 300 seconds, and is then hot-dip galvanized.

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 of thermomechanical shaping a final product with very high strength including the steps of: providing a coated hot-rolled and/or cold-rolled steel strip or sheet including (all percentages in wt. %): 0.04%<carbon<0.5%, 0.5%<manganese<3.5%, silicon<1.0%, 0.01%<chromium<1%, titanium<0.2%, aluminium<0.2%, phosphorus<0.1%, nitrogen<0.015% N, sulphur<0.05%, boron<0.015%, unavoidable impurities, balance iron, the steel being coated with a zinc alloy coating layer, wherein the zinc alloy includes 0.3-4.0% Mg and 0.05-6.0% Al; optionally at most 0.2% of one or more additional elements; unavoidable impurities; the remainder being zinc; cutting the steel sheet to obtain a steel sheet blank; thermomechanical shaping of the steel sheet blank to a final product with its final properties.

Abstract: The present invention relates to high-manganese steel with superior weldability and to a method for manufacturing hot-dipped galvanized steel sheets from same. The high-manganese steel according to one aspect of the present invention is characterized by comprising, by weight %: C: 0.3-1%; Mn: 8-25%; Al: 1-8%; Si: 0.1-3.0%; Ti: 0.01-0.2%; Sn: 0.06-0.2%; and B: 0.0005-0.01%, with the remainder being Fe and unavoidable impurities. The present invention may provide high-manganese hot-dipped galvanized steel sheets, having high strength and processability and superior surface quality, which can prevent plating failures caused by manganese.

Abstract: The present invention provides a high-strength galvanized steel sheet with maximum tensile strength of 900 MPa or more. The high-strength galvanized steel sheet has an alloyed galvanized layer formed on a surface of a base steel sheet containing predetermined amounts of C, Si, Mn, P, S, Al, N, O with a balance being constituted of iron and inevitable impurities, in which in a structure of the base steel sheet, retained austenite is limited to 8% or less in volume fraction, kurtosis K* of the hardness distribution between 2% hardness and 98% hardness is ?0.30 or less, a ratio between Vickers hardness of surface layer of the base steel sheet and Vickers hardness of ¼ thickness of the base steel sheet is 0.35 to 0.70, and a content of iron in the alloyed galvanized layer is 8 to 12% in mass %.

Abstract: A hot-dip galvanized cold-rolled steel sheet has a tensile strength of 750 MPa or higher, a composition consisting, in mass percent, of C: more than 0.10% and less than 0.25%, Si: more than 0.50% and less than 2.0%, Mn: more than 1.50% and 3.0% or less, and optionally containing one or more types of Ti, Nb, V, Cr, Mo, B, Ca, Mg, REM, and Bi, P: less than 0.050%, S: 0.010% or less, sol. Al: 0.50% or less, and N: 0.010% or less, and a main phase as a low-temperature transformation product and a second phase as retained austenite. The retained austenite volume fraction is more than 4.0% and less than 25.0% of the whole structure, and has an average grain size of less than 0.80 ?m. A number density of retained austenite grains having a grain size of 1.2 ?m or more is 3.0?10?2/?m2 or less.

Abstract: A high strength hot dip galvanised steel strip having, in mass percent, the following elements: 0.13-0.19% C; 1.70-2.50% Mn; max 0.15% Si; 0.40-1.00% Al; 0.05-0.25% Cr; 0.01-0.05% Nb; max 0.10% P; max 0.004% Ca; max 0.05% S; max 0.007% N; and optionally at least one of the following elements: max 0.50% Ti, max 0.40% V, max 0.50% Mo, max 0.50% Ni, max 0.50% Cu, max 0.005% B, the balance being Fe and inevitable impurities; wherein 0.40%<Al+Si<1.05% and Mn+Cr>1.90%. This steel offers improved formability at a high strength, has a good weldability, and surface quality together with a good producability and coatability.

Abstract: Steel strip provided with a hot dip galvanized zinc alloy coating layer, in which the coating of the steel strip is carried out in a bath of molten zinc alloy, the zinc alloy in the coating consisting of: 0.3-2.3 weight % magnesium; 0.6-2.3 weight % aluminum; optional <0.2 weight % of one or more additional elements; unavoidable impurities; the remainder being zinc in which the zinc alloy coating layer has a thickness of 3-12 ?m.

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: Provided are: a galvannealed steel sheet, reliably and sufficiently improved in the adhesiveness of a plated layer with a base steel sheet, as a galvannealed steel sheet, prepared by using a high-strength steel sheet as a base material; and a method for producing the galvannealed steel sheet. The galvannealed steel sheet wherein a galvannealed layer is formed on a base steel sheet including a high-strength steel having predetermined component composition; the average amount of Fe in the galvannealed layer is in a range of 8.0 to 12.0%; and the absolute value ?Fe of a difference between the amount of Fe in the vicinity of an interface with the base steel sheet (the amount of Fe in the vicinity of an internal side) and the amount of Fe in the vicinity of the external surface of the plated layer (the amount of Fe in the vicinity of an external side) in the plated layer is in a range of 0.0 to 3.0%.

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: The present invention is to produce press hardened parts having excellent properties while avoiding a peeling of a plated layer or an intergranular cracking of a base material during a press forming, in such a manner that when a surface-treated steel sheet in which a Zn—Fe-based plated layer is formed on a surface of a base steel sheet is manufactured by a press hardening process, the forming is started after the surface-treated steel sheet is heated to a temperature that is not lower than an Ac1 transformation point of the base steel sheet and 950° C. or lower and the surface-treated steel sheet is then cooled to a temperature that is not higher than a solidifying point of the plated layer depending on the content of Fe in the plated layer.

Abstract: A method for manufacturing a corrosion-protected steel molded part with an at least predominantly bainitic structure is provided. The method includes heating a blank of sheet steel to an austenization temperature; compression molding the blank while simultaneously cooling, so as to obtain a molded part; and bainitizing the molded part in a zinc coating bath.

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: 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: There is provided a heating device, in particular an austenitization device, for a plant for hot forming blanks, wherein the heating device is for locally heating, in particular austenitization, regions of the blanks and has at least one burner. Also included is means for moving the burner and/or the flame of the burner to the regions of the blank which are to be subjected to local heating.

Abstract: The present invention relates to a hot press forming steel plate made of a composition comprising: 0.3-1.0 wt % of C; 0.0-4.0 wt % of Mn; 1.0-2.0 wt % of Si; 0.01-2.0 wt % of Al; 0.015 wt % or less of S; 0.01 wt % or less of N; and the remainder being Fe and unavoidable impurities. Further, the present. invention relates to a method for manufacturing the hot press forming steel plate, characterized by comprising the steps of: heating, to between 1100 and 1300° C., a steel slab having the composition; performing hot rolling finishing between. an Ar3 transformation point and 950° C.; and performing winding between MS and 720° C. Further, the present invention. relates to a hot press formed member characterized by having the composition, and having a dual phase microstructure made of bainite and residual austenite.

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: A process for manufacturing a ferritic hot rolled steel strip is provided. The process includes providing a steel slab, hot rolling the slab to produce a transfer bar and ferritic hot rolling the transfer bar to produce hot rolled strip. The ferritic hot rolled strip is coiled at temperatures between 580-780° C. and has a yield strength between 130-210 MPa, a tensile strength greater than 260 MPa, a uniform elongation greater than 15%, a total elongation to failure greater than 30%, and an n-value greater than 0.2.

Abstract: A method of thermomechanical shaping a final product with very high strength including the steps of: providing a coated hot-rolled and/or cold-rolled steel strip or sheet including (all percentages in wt. %): 0.04%<carbon<0.5%, 0.5%<manganese<3.5%, silicon<1.0%, 0.01%<chromium<1%, titanium<0.2%, aluminum<0.2%, phosphorus<0.1%, nitrogen<0.015% N, sulphur<0.05%, boron<0.015%, unavoidable impurities, balance iron, the steel being coated with a zinc alloy coating layer, wherein the zinc alloy consists of 0.3-4.0% Mg and 0.05-6.0% Al; optionally at most 0.2% of one or more additional elements; unavoidable impurities; the remainder being zinc; cutting the steel sheet to obtain a steel sheet blank; thermomechanical shaping of the steel sheet blank to a final product with its final properties.

Abstract: The present invention is related to a steel composition, a process for producing a steel product having said composition, and said steel product itself. According to the invention, a cold-rolled, possibly hot dip galvanized steel sheet is produced with thicknesses lower than 1 mm, and tensile strengths between 800 MPa and 1600 MPa, while the A80 elongation is between 5 and 17%, depending on the process parameters. The composition is such that these high strength levels may be obtained, while maintaining good formability and optimal coating quality after galvanising. The invention is equally related to a hot rolled product of the same composition, with higher thickness (typically about 2 mm) and excellent coating quality after galvanising.

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.