Abstract: A method of manufacturing a high strength cold rolled steel sheet includes hot-rolling and cold-rolling a steel slab annealing the steel sheet at an annealing temperature of 750° C. to 830° C.; subjecting the steel sheet to first cooling at an average cooling rate of 3° C./sec to 40° C./sec in a temperature range from the annealing temperature to 480° C.; subjecting the steel sheet to second cooling at an average cooling rate of 8° C./sec to 80° C./sec in a temperature range from 480° C. to Tc (° C.) given by formula (6): Tc=435?40×[% Mn]?30×[% Cr]?30×[% V]??(6) wherein [% A] is the content (% by mass) of alloying element A; and subjecting the steel sheet to third cooling at an average cooling rate of 0.3° C./sec to 30° C./sec in a temperature range from Tc (° C.) to 200° C.

Abstract: A method for producing a hot-dip zinc alloy coated steel sheet excellent in coating adhesion, comprising: hot-rolling a steel sheet, subjecting the base sheet for coating to a reduction heat treatment, and subjecting the base sheet for coating to hot-dip zinc alloy coating. The hot-dip alloy coated steel sheet is excellent in coating adhesion, by using, as a base sheet for coating, a steel sheet that is imparted with resistance to liquid metal embrittlement cracking by adding B. The hot-dip zinc alloy coated steel sheet excellent in coating adhesion contains at least one of a Si simple oxide, a Mn simple oxide, a Cr simple oxide, a Si—Mn composite oxide, a Si—Cr composite oxide, a Mn—Cr composite oxide, and a Si—Mn—Cr composite oxide in a portion within 10 ?m from an interface between a steel sheet as a base sheet and a hot-dip galvanized layer formed on a surface thereof.

Abstract: In one aspect of the invention, a torsion bar assembly is provided. The assembly includes a first shaft having a first bore, a second shaft having a second bore, the second shaft operatively coupled to the first shaft, and a torsion bar positioned within the first and second bores. The torsion bar includes a splined first end having a first diameter extending to a first end face having a diameter generally the same as the first diameter, a splined second end having a second diameter extending to a second end face having a diameter generally the same as the second diameter, and an active diameter extending between the splined first end and the splined second end. The torsion bar is fabricated from a material having a hardness greater than 45 Rockwell C-Scale.

Abstract: A high strength, high toughness steel alloy is disclosed. The alloy has the following weight percent composition. Element C 0.30-0.47 Mn 0.8-1.3 Si 1.5-2.5 Cr 1.5-2.5 Ni 3.0-5.0 Mo + ½ W 0.7-0.9 Cu 0.70-0.90 Co ?0.01 max. V + ( 5/9) × Nb 0.10-0.25 Ti 0.005 max. Al 0.015 max. Fe Balance Included in the balance are the usual impurities found in commercial grades of steel alloys produced for similar use and properties including not more than about 0.01% phosphorus and not more than about 0.001% sulfur. Also disclosed is a hardened and tempered article that has very high strength and fracture toughness. The article is formed from the alloy having the broad weight percent composition set forth above. The alloy article according to this aspect of the invention is further characterized by being tempered at a temperature of about 500° F. to 600° F.

Abstract: A thick-walled high-strength hot rolled steel sheet has a high tensile strength TS of 521 MPa or more and excellent low-temperature toughness. The steel material forming the sheet contains 0.02%-0.08% C, 0.01%-0.10% Nb, and 0.001%-0.05% Ti and is heated; C, Ti, and Nb satisfies (Ti+(Nb/2))/C<4.

Abstract: Disclosed is a high strength steel sheet having excellent hydrogen embrittlement resistance. The steel sheet has a tensile strength of 1180 MPa or more, and satisfies the following conditions: with respect to an entire metallographic structure thereof, bainite, bainitic ferrite and tempered martensite account for 85 area % or more in total; retained austenite accounts for 1 area % or more; and fresh martensite accounts for 5 area % or less (including 0 area %).

Abstract: The present invention provides a cold rolled steel sheet. The steel sheet has a strength greater than 1000 MPa, a uniform elongation greater than 12% and a V-bendability greater than 90°. The composition of the steel sheet includes, expressed in per cent by weight, 0.15%?C?0.25%, 1.8%?Mn?3.0%, 1.2%?Si?2%, 0%?Al?0.10%, 0%?Cr?0.50%, 0%?Cu?1%, 0%?Ni?1%, 0%?S?0.005%, 0%?P?0.020%, Nb?0.015%, Ti?0.020%, V?0.015%, Co?1%, N?0.008%, B?0.001% whereby Mn+Ni+Cu?3%. The remainder of the composition consists of iron and inevitable impurities resulting from processing. The microstructure includes, in area percentage, 5 to 20% polygonal ferrite, 10 to 15% residual austenite, 5 to 15% martensite and a balance of bainite. The bainite is in the form of laths and includes carbides between the laths. A number N of inter-lath carbides larger than 0.1 micrometers per unit of surface area is less than or equal to 50000/mm2. A fabrication method and a motor vehicle are also provided.

Abstract: A carbon steel wire with unprecedentedly high strength and excellent ductility and fatigue resistance, a process for producing the same, and a method of evaluating the same are provided. Provided is a carbon steel wire having a carbon content of 0.50 to 1.10% by mass, wherein the ratio of the hardness of the surface layer portion on a cross section and the hardness of the surface layer portion on a longitudinal section is represented by a coefficient X1, and the ratio of the hardness of the center portion on the cross section and the hardness of the center portion on the longitudinal section is represented by a coefficient X2, wherein X1 and X2 satisfy the following expressions: 0.9<coefficient X1?1.10, and 0.9<coefficient X2?1.10, and wherein the carbon steel wire has a tensile strength of 4000 MPa or higher.

Abstract: Provided is a wire rod for use in mechanical structure connections, vehicle components, or the like, and more particularly, to a wire rod which has superior toughness without being subjected to a heat treatment, and the strength of which is ensured through a cold-drawing process. Tot his end, provided are a high-toughness cold-drawn non-heat-treated wire rod and a method for manufacturing the same, wherein the wire rod comprises in % by weight: 0.2 to 0.3% of carbon (C), 0.1 to 0.2% of silicon (Si), 2.5 to 4.0% of manganese (Mn), 0.035% or less (but not 0%) of phosphorus (P), 0.04% or less (but not 0%) of sulfur (S), the remainder being iron (Fe) and unavoidable impurities.

Abstract: The present disclosure discloses a heat treatment method for a bainitic turnout rail, which includes: naturally cooling the turnout rail at a temperature in an austenite region after being finishing rolled to 450-480° C. at a tread center of a rail head of the turnout rail; accelerated cooling the naturally cooled turnout rail to 230-270° C. at the tread center of the rail head, a cooling rate at the tread center and a non-working side of the rail head being 1.5-5.0° C./s, a cooling rate at the working side of the rail head increasing by 0.1-1.0° C./s based on 1.5-5.0° C./s; continuously accelerated cooling the working side, the tread center and the non-working side of the rail head at a cooling rate of 0.05-0.25° C./s to decrease a temperature of the tread center of the rail head to 265-270° C.; and finally, naturally cooling the turnout rail to an ambient temperature.

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 high strength cold rolled steel sheet includes a chemical composition containing, by mass %, C: 0.010% or more and 0.060% or less, Si: more than 0.5% and 1.5% 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 0.500% or less, N: 0.0100% or less, Nb: 0.010% or more and 0.100% or less, Ti: 0.015% or more and 0.150% or less and the balance comprising Fe and inevitable impurities. The microstructure includes, in area fraction, 70% or more of a ferrite phase and 3% or more of a martensite phase. The tensile strength is 440 MPa or more and an average r value is 1.20 or more.

Abstract: The invention relates to a cold-rolled carbon steel comprising (in % by weight) C 0.63-0.85%, max. 0.40% Si, 0.20-0.90% Mn, max. 0.035% P, max. 0.035% S, max. 0.060% Al, max. 0.40% Cr, 0.003-0.010% N, preferably 0.005-0.008%, and a maximum of 0.12% of at least one micro-alloying element, the remainder being iron and steel production-related pollutants. Possible micro-alloying elements are Ti, Nb, V and optionally Zr. A carbon steel of the type is cold-rolled into texture-rolled strip steel with a high cold reduction degree and can be used in particular as a material for coiling springs or other components having spring properties.

Abstract: A roller bearing element for a large roller bearing includes the following features: at least one contact zone for a roller bearing counter element, the contact zone has an induction-hardened surface layer, the roller bearing element is comprised of a steel, which includes an admixture of carbon of at least 0.46 mass %.

Abstract: The invention provides a hot-forging micro-alloyed steel which achieves excellent fracture-splitability and machinability, without impairing productivity or mechanical properties and without the addition of Pb or the like. It also provides a component made of hot-forged micro-alloyed steel. The hot-forging micro-alloyed steel contains, in mass %, C: from 0.35 to 0.60%, Si: 0.50 to 2.50%, Mn: 0.20 to 2.00%, P: 0.010 to 0.150%, S: 0.040 to 0.150%, V: 0.10 to 0.50%, Zr: over 0.0023 to 0.0050%, Ca: 0.0005 to 0.0050% and N: 0.0069 to 0.0200%, Al being limited to less than 0.010%, and a balance substantially of Fe and unavoidable impurities.

Abstract: A steel wire rod which is a material of steel wires includes, as a metallographic structure, by area %, 95% to 100% of a pearlite, wherein an average pearlite block size at a central portion of the steel wire rod is 1 ?m to 25 ?m, an average pearlite block size at a surface layer portion of the steel wire rod is 1 ?m to 20 ?m, and, when a minimum lamellar spacing of the pearlite at the central portion of the steel wire rod is S in unit of nm and when a distance from a peripheral surface of the steel wire rod to a center is r in unit of mm, S<12r+65 is satisfied.

Abstract: A steel sheet for forming having low-temperature heat treatment property, in which heat treatment is performed within a range of lower temperature than a conventional steel sheet in the event of hot press forming or post-heat treatment after cold forming, a method of manufacturing the same, and a method of manufacturing parts using the same. The steel sheet has a composition of, by weight, carbon (C): 0.15 to 0.35%, silicon (Si): 0.5% or less, manganese (Mn): 1.5 to 2.2%, phosphorus (P): 0.025% or less, sulfur (S): 0.01% or less, aluminum (Al): 0.01 to 0.05%, nitrogen (N): 50 to 200 ppm, titanium (Ti): 0.005 to 0.05%, tungsten (W): 0.005 to 0.1%, and boron (B): 1 to 50 ppm, wherein Ti/N: less than 3.4, where Ti/N is the atomic ratio of the corresponding elements, Ceq expressed by the following formula ranges from 0.48 to 0.58, and temperature Ar3 ranges from 670° C. to 725° C. Wherein Ceq C+Si/24+Mn/6+Ni/40+Cr/5+V/14 where C, Si, Mn, Ni, Cr and V indicate the contents (wt %) of the respective elements.

Abstract: Disclosed are methods, systems and apparatus for manufacturing complex three dimensional open structures by cold forming the component from unhardened metal stock and then selectively heating and quenching the metal to provide the desired strength profile across the component. The metal is initially formed of unheated and unhardened metal through a combination of rolling, stamping and/or milling operations to produce a component having a complex three dimensional open structure. The formed component is then hardened in strategically predetermined areas by sequentially heating and quenching the predetermined areas of the component. The heating and cooling elements are, in turn, provided on at least one robotic apparatus configured for moving the elements across the surface of the component in a manner sufficient to achieve the desired pattern of hardened and unhardened regions across the component.

Abstract: A high strength hot-rolled steel sheet has a tensile strength of not less than 780 MPa and exhibits excellent stretch flangeability and excellent fatigue resistance. A steel has a composition containing C at 0.05 to 0.15%, Si at 0.2 to 1.2%, Mn at 1.0 to 2.0%, P at not more than 0.04%, S at not more than 0.005%, Ti at 0.05 to 0.15%, Al at 0.005 to 0.10% and N at not more than 0.007%.

Abstract: A casting of a white cast iron alloy which includes the following alloy composition, in weight %: chromium: 12-25%; carbon: 1.5-6%; manganese: 2-7%; silicon: up to 1.5%; molybdenum: up to 2; nickel: up to 4%; microalloying elements selected from the group of titanium, zirconium, niobium, boron, vanadium, and tungsten: up to 2% of each of one or more of the elements; and iron: balance. The microstructure of the casting has 15-60 vol % eutectic carbides and primary carbides dispersed in a ferrous matrix of martensite and is at least substantially free of pearlite.

Abstract: The invention provides an alloy steel having the following composition: Ni 5-14 wt %; Cr 4-16 wt %; Co 7-14 wt %; Mo 1-5 wt %; W 0-5 wt %; Ti 0-0.8 wt %; Al 0.1-3 wt %; the balance being Fe save for incidental impurities. This provides an ultra-high strength corrosion resistant steel with good toughness, which does not significantly creep at temperatures up to 450° C. The high quantity of alloying to elements, particularly chromium, also gives the alloy good corrosion resistance. The alloy is particularly suitable for main shafts of gas turbine engines.

Abstract: A method of manufacturing high strength steel wire for cold forging containing 0.15-0.40 wt % of C, less than 1.5 wt % of Si, 0.30-2.0 wt % of Mn, less than 0.03 wt % of P, and less than 0.03 wt % of S. After initial cold-drawing, the wire rod is heated in a series of high frequency induction heating devices over the Ac3 transformation point for 30-90 seconds. The wire rod is then rapidly cooled and tempered at a temperature of from 500° C. to the A1 transformation point for 30-90 seconds. The wire rod is then cooled to achieve a tensile strength of 1,100-1, 400 MPa. The wire rod is then cold-drawn at an area reduction rate in excess of 25% and up to 40% to yield a tensile strength of 1,200-1,600 MPa, with improved service life of the mold.

Abstract: This high-strength steel sheet has a component composition containing, in mass %, 0.02 to 0.3% C, 1 to 3% Si, 1.8 to 3% Mn, 0.1% or less P, 0.01% or less S, 0.001 to 0.1% Al, and 0.002 to 0.03% N, the remainder being iron and impurities. The high-strength steel sheet has a structure containing, in terms of area ratio relative to the entire structure, each of the following phases: 50 to 85% bainitic ferrite; 3% or more retained austenite (?); 10 to 45% martensite and the aforementioned retained austenite (?); and 5 to 40% ferrite. The ratio between the Mn concentration (Mn?R) in the retained austenite (?) and the average Mn concentration (Mnav) in the entire structure is 1.2 or more (Mn?R/ Mnav) based on the Mn concentration distribution obtained by means of EPMA line analysis. As a consequence, the high-strength steel sheet exhibits strength of 980 MPa or more and exerts excellent deep drawability.

Abstract: Hot-rolled steel has a chemical composition containing, by mass %, C: 0.18% or more and 0.29% or less, N: 0.0050% or less, Ti: 0.002% or more and 0.05% or less, B: 0.0005% or more and 0.0050% or less, and appropriately controlled amounts of Si, Mn, P, S, Al, and a tensile strength of 500 MPa or less with a variation in tensile strength of 60 MPa or less throughout a region including the edges in the width direction of the steel sheet, and having excellent cold formability and hardenability.

Abstract: The present invention relates to an axle forged from seamless tubes, with a chemical composition suitable to guarantee high fatigue strength, improved yield strength and tensile strength, and having reduced weight for use on railroad vehicles. The present invention further relates to a process of manufacturing the axle forged from seamless steel tube with high fatigue strength, improved yield strength and tensile strength, and having reduced weight for use on railroad vehicles, which is produced from pig iron or scrap, casting, reheating furnace, perforation of billets, elongation of perforated billets, hollow finishing, forging and finish machining, which includes a supporting and centering chamfer at the inner edge of the inspection bore of the end and smooth recess in the entrance of the threaded bores.

Abstract: [Summary] [Object] There are provided electric resistance welded oil country tubular goods having strength corresponding to API specification 5CT P110 without a heat treatment being performed on the whole steel pipe and further having excellent toughness, and a manufacturing method of an electric resistance welded oil country tubular goods. [Solution] Electric resistance welded oil country tubular goods according to the present invention have a chemical composition that contains, in mass %, C: 0.05 to 0.12%, Si: 0.03 to 0.5%, Mn: 0.80 to 2.2%, P: 0.03% or less, S: 0.003% or less, Al: 0.08% or less, Nb: 0.01% to 0.10%, Ti: 0.005 to 0.03%, B: 0.0005 to 0.0030%, and N: 0.008% or less, and in which Ti>3.4 N is satisfied, its balance is composed of Fe and inevitable impurities, and, VC90 is 15 to 40.

Abstract: In a non-oriented electrical steel sheet, Si: not less than 1.0 mass % nor more than 3.5 mass %, Al: not less than 0.1 mass % nor more than 3.0 mass %, Ti: not less than 0.001 mass % nor more than 0.01 mass %, Bi: not less than 0.001 mass % nor more than 0.01 mass %, and so on are contained. (1) expression described below is satisfied when a Ti content (mass %) is represented as [Ti] and a Bi content (mass %) is represented as [Bi]. [Ti]?0.8×[Bi]+0.

Abstract: Disclosed is a steel sheet, containing: Si: 0.20-2% (the term “%” herein means “mass %”, the same is true hereinbelow), Mn: 1-2.5%, a total mass of Si and Mn being 1.5% or more, and O: 0.002% or less (exclusive of 0%), C: 0.02-0.25%, P: 0.1% or less (exclusive of 0%), S: 0.05% or less (exclusive of 0%), Al—0.02-0.2%, and N: 0.0015-0.015%. The steel sheet of the invention can be advantageously used for forming wide beads even in high-speed arc welding of 100 cm/min or higher.

Abstract: A probability in which a stress amplitude ?p of an operating stress exceeds a stress amplitude ?w of a fatigue strength (a fatigue strength excess probability pV0 of a virtual cell) at each virtual cell in which a region of a machine component is equally divided so that one inclusion is contained therein and having a virtual unit volume V0 is derived on an assumption that a distribution function of an inclusion size ?{square root over ( )}area follows a generalized Pareto distribution. Then a probability in which the stress amplitude ?p of the operating stress exceeds the stress amplitude ?w of the fatigue strength (a fatigue strength excess probability pfV of the machine component) in at least one virtual cell is derived from the fatigue strength excess probability pV0.

Abstract: In a steel sheet having a specific chemical composition and having a microstructure including ferrite that is a soft first phase by 20-50% in terms of the area ratio, the remainder being tempered martensite and/or tempered bainite that is a hard second phase, the microstructure of steel of a surface layer section of the steel sheet from the surface to the depth of 100 ?m and a center section of t/4-3t/4 (t is the sheet thickness) is controlled.

Abstract: A quenched steel pipe member is formed of a GI galvanized steel pipe, in a middle section in a longitudinal direction of the GI galvanized steel pipe, a cross-section perpendicular to the longitudinal direction has a substantially V shape including a contact section at which opposite parts of an inner circumferential surface of the GI galvanized steel pipe come into contact with each other, the contact section is bonded using a Fe—Zn alloy phase, and a micro Vickers hardness at a location 50 ?m deep from a base material surface layer is 95% or more of a micro Vickers hardness at a location 200 ?m deep from the base material surface layer.

Abstract: The invention concerns a cold-rolled aluminum killed steel sheet, which includes by weight between 0.003 and 0.130% of carbon, between 0.10 and 1% of manganese, between 0.010 and 0.100% of aluminum, between 0.0015 and 0.0140% nitrogen, the remainder being of iron and impurities resulting from the manufacturing, and which has a content of carbon in solid solution (Css) of at least 50 ppm, as well as a method of manufacturing packaging from said sheet.

Abstract: A multiphase steel sheet has a steel composition containing, in percent by mass, more than 0.015% to less than 0.100% of carbon, less than 0.40% of silicon, 1.0% to 1.9% of manganese, more than 0.015% to 0.05% of phosphorus, 0.03% or less of sulfur, 0.01% to 0.3% of soluble aluminum, 0.005% or less of nitrogen, less than 0.30% of chromium, 0.0050% or less of boron, less than 0.15% of molybdenum, 0.4% or less of vanadium, 0.02% or less of titanium, wherein [Mneq] is 2.0 to 2.8, the balance being iron and incidental impurities.

Abstract: A steel for an induction hardening including, by mass %, C: more than 0.75% to 1.20%, Si: 0.002 to 3.00%, Mn: 0.20 to 2.00%, S: 0.002 to 0.100%, Al: more than 0.050% to 3.00%, P: limited to 0.050% or less, N: limited to 0.0200% or less, O: limited to: 0.0030% or less, and the balance composing of iron and unavoidable impurities, wherein an Al content and a N content satisfy, by mass %, Al?(27/14)×N>0.050%.

Abstract: A method for manufacturing a hot-rolled sheet attains grain refinement of the steel sheet whose grain size is extremely fine. In particular, a ferrite grain size of less than average 2 ?m is obtained, which is not laminar but has ferrite grains with equiaxed morphology and exhibits high formability in forming. The method comprises the steps of rolling and cooling, wherein the rolling reductions, cooling steps, and temperature are closely regulated. A hot rolled sheet made from the method of manufacturing has a controlled ferrite grain in different regions of sheet thickness.

Abstract: A steel material superior in high temperature characteristics and toughness is provided, that is, a steel material containing, by mass %, C: 0.005% to 0.03%, Si: 0.05% to 0.40%, Mn: 0.40% to 1.70%, Nb: 0.02% to 0.25%, Ti: 0.005% to 0.025%, N: 0.0008% to 0.0045%, B: 0.0003% to 0.0030%, restricting P: 0.030% or less, S: 0.020% or less, Al: 0.03% or less, and having a balance of Fe and unavoidable impurities, where the contents of C and Nb satisfy C—Nb/7.74?0.02 and Ti-based oxides of a grain size of 0.05 to 10 ?m are present in a density of 30 to 300/mm2.

Abstract: A steel for oil country tubular goods includes, as a chemical composition, by mass %, C, Si, Mn, Al, Mo, P, S, O, N, and a balance containing Fe and impurities, wherein a full width at half maximum HW of a crystal plane corresponding to a (211) crystal plane of an ? phase and a carbon content expressed in mass % in the chemical composition satisfy HW×C1/2?0.38, the carbon content and a molybdenum content expressed in mass % in the chemical composition satisfy C×Mo?0.6, a number of M2C carbides having a hexagonal crystal structure and having an equivalent circle diameter of 1 nm or more is 5 pieces or more per one square micron, and an yield strength is 758 MPa or more.

Abstract: In a high strength cold-rolled steel plate having a specific chemical composition, a soft first phase (ferrite) has an area ratio of 20-50%, the remainder being a hard second phase (tempered martensite and/or tempered bainite), among all the ferrite grains, ferrite grains that have an average grain diameter of 10-25 ?m account for a total area ratio of 80% or more, the number of the cementite grains that have an equivalent circle diameter of 0.3 ?m or more is more than 0.15 piece and 1.0 piece or less per 1 ?m2 of ferrite, and the tensile strength is 980 MPa or more.

Abstract: The present invention provides ultralow carbon thin gauge steel sheet and a method for producing the same where coalescence and growth of inclusions in the molten steel are prevented and the inclusions are finely dispersed in the steel sheet, whereby surface defects and cracks at the time of press forming are prevented, growth of recrystallized grains at the time of continuous annealing is promoted, and a high r value (r value?2.0) and elongation (total elongation?50%) are exhibited, that is, ultralow carbon thin gauge steel sheet excellent in surface conditions, formability, and workability comprised of, by mass %, 0.00030.003%?C?0.003%, Si?0.01%, Mn?0.1%, P?0.02%, S?0.01%, 0.0005%?N?0.0025%, 0.01%?acid soluble Ti?0.07%, acid soluble Al?0.003%, and 0.002%?La+Ce+Nd?0.02% and a balance of iron and unavoidable impurities, said steel sheet characterized by containing at least cerium oxysulfite, lanthanum oxysulfite, and neodymium oxysulfite.

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: A steel wire for spring is provided which exhibits high strength even without adding a large amount of alloy elements, and is for obtaining a cold winding spring having excellent coiling performance and improved hydrogen embrittlement resistance. The steel wire for spring is characterized in that C: 0.40-0.65% (mass %), Si: 1.0-3.0%, Mn: 0.6-2.0%, P: 0.015% or less (exclusive of 0%), S: 0.015% or less (exclusive of 0%), and Al: 0.015 percent by mass or less (excluding 0%) of S, and Al: 0.001-0.10% are satisfied, with the remainder consisting of iron and inevitable impurities, tempered martensite: 70 area % or more and retained austenite: 6-15 area % with respect to the total microstructure, the prior austenite grain size number obtained by a method stipulated in JIS G 0551 is No. 10.0 or more, and the tensile strength is 1,900 MPa or more.

Abstract: A steel sheet for cans containing 0.0060 to 0.01 mass % C and 0.02 to 0.12 mass % Nb and having the following characteristics: (i) an average ferrite grain size in a cross section in the rolling direction in a region from a surface layer of the steel sheet to a position ¼ of a sheet thickness away from the surface layer of the steel sheet is 7 ?m to 10 ?m or less, and (ii) an average ferrite grain size in a cross section in the rolling direction in a region from the position ¼ of a sheet thickness away from the surface layer of the steel sheet to a sheet thickness center portion of the steel sheet is 15 ?m or less, wherein the average ferrite grain size (1) is smaller than the average ferrite grain size (2).

Abstract: A high strength press-formed member includes a steel sheet constituting the member including a composition including by mass %, C: 0.12% to 0.69%, 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, N: 0.010% or less, Si+Al: at least 0.

Abstract: The present invention solves the problem of melting of Al in heating before hot-stamping, which had been a problem in the past in applying hot-stamping to Al-plated steel sheet, and provides Al-plated steel sheet for hot-stamping and a method of hot-stamping using that Al-plated steel sheet to solve the problem of delayed fracture due to residual hydrogen, and, furthermore, a method of a rapid heating hot-stamping using that Al-plated steel sheet. The Al-plated steel sheet of the present invention is produced by annealing the Al-plated steel sheet as coiled in a box-anneal furnace for the time and at the temperature indicated in FIG. 5, and alloying of a plated Al and a steel sheet. Further, a method of rapid heating hot-stamping in the present invention is characterized by cutting out a stamping blank of an Al-plated steel sheet, and heating that blank in heating before hot-stamping by an average temperature with a rising rate of 40° C./sec or more and a time of exposure to an environment of 700° C.

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: A cold rolled steel sheet satisfying on the basis of percent by mass the chemical composition of 0.06-0.6% C, 0.1-2% Si, 0.01-3% Al, 1-4% Si+Al, 1-6% Mn, Si/Mn?0.40, in which there exists 10 or more pieces/100 ?m2 of Mn—Si composite oxide having Mn—Si atom ratio (Mn/Si) of 0.5 or over and major axis of from 0.01 ?m to 5 ?m and also having a covering ratio of 10% or below at which the surface of the steel sheet is covered with oxide containing Si as the main component.

Abstract: A steel sheet suitable as a starting material for a vehicle impact absorbing member with high absorption of impact energy and resistance to cracking contains, by mass %, C: 0.08-0.30%, Mn: 1.5-3.5%; Si+Al: 0.50-3.0%, P: 0.10% or less, S: at most 0.010%, and N: at most 0.010%, and optionally, one or more types selected from Cr: at most 0.5%, Mo: at most 0.5%, B: at most 0.010%, Ti: less than 0.04%, Nb: less than 0.030%, V: less than 0.5%, Ca: at most 0.010%, Mg: at most 0.010%, REM: at most 0.050%, and Bi: at most 0.050%. The microstructure contains, by area %, bainite: more than 50%, martensite: 3-30%, and retained austenite: 3-15%, the remainder comprising ferrite having an average grain diameter of less than 5 mm. The product of uniform elongation and hole expansion ratio is at least 300%2 and 5% effective flow stress is at least 900 MPa.

Abstract: A method for laser heat treatment of high tensile steel is provided to improve for improving formability. The method includes performing a heat treatment by irradiating a surface of a high tensile steel blank that includes a martensite structure and a ferrite structure with a laser to decrease a fraction of the martensite structure and increase a fraction of the ferrite structure. In addition, the method includes slowly cooling the blank to temper or anneal the heat-treated blank and subjecting the cooled blank to cold press forming.

Abstract: A steel rail includes: by mass %, higher than 0.85% to 1.20% of C; 0.05% to 2.00% of Si; 0.05% to 0.50% of Mn; 0.05% to 0.60% of Cr; P?0.0150%; and the balance consisting of Fe and inevitable impurities, wherein 97% or more of a head surface portion which is in a range from a surface of a head corner portion and a head top portion as a starting point to a depth of 10 mm has a pearlite structure, a Vickers hardness of the pearlite structure is Hv320 to 500, and a CMn/FMn value which is a value obtained by dividing CMn [at. %] that is a Mn concentration of a cementite phase in the pearlite structure by FMn [at. %] that is a Mn concentration of a ferrite phase is equal to or higher than 1.0 and equal to or less than 5.0.

Abstract: This case hardening steel has a chemical composition including, by mass %: C: 0.1 to 0.6%; Si: 0.02 to 1.5%; Mn: 0.3 to 1.8%; P: 0.025% or less; S: 0.001 to 0.15%; Al: over 0.05 to 1.0%; Ti: 0.05 to 0.2%; N: 0.01% or less; and O: 0.0025% or less, and further including, by mass %, one or more of Cr: 0.4 to 2.0%, Mo: 0.02 to 1.5%, Ni: 0.1 to 3.5%, V: 0.02 to 0.5%, and B: 0.0002 to 0.005%, and the balance consisting of iron and unavoidable impurities.