Abstract: Press hardened steels exhibit increased strength in the press hardened steel parts without a corresponding decrease in elongation. Substitutional elements are included in the steel composition to increase the strength of martensite through a combination of substitutional solute strengthening and a reduction in softening that results from autotempering. Softening as a result of autotempering is minimized by suppression of the martensite start (Ms) temperature through the alloying. As a result of the increased hardenability in the proposed compositions that results from various additions of manganese, chromium, molybdenum, and niobium, the steel compositions permit a boron-free press hardening steel.

Abstract: A method for manufacturing a high-strength steel bar can include the steps of: reheating a steel slab at a temperature ranging from 1000° C. to 1100° C., the steel slab including a certain amount of carbon (C), silicon (Si), manganese (Mn), phosphorus (P), sulfur (S), chromium (Cr), copper (Cu), nickel (Ni), molybdenum (Mo), aluminum (Al), vanadium (V), nitrogen (N), antimony (Sb), tin (Sn), and iron (Fe) and other inevitable impurities, The method can further include finish hot-rolling the reheated steel slab at a temperature of 850° C. to 1000° C., and cooling the hot-rolled steel to a martensite transformation start temperature (Ms (° C.)) through a tempcore process.

Abstract: A lower mold includes: refrigerant ejection ports in its press-molding surface; refrigerant guide grooves in the press-molding surface to guide a refrigerant ejected from the refrigerant ejection ports to an outer portion of the press-molding surface with the refrigerant being in contact with a workpiece; a single connecting groove connected to the refrigerant guide grooves and formed at the outer portion of the press-molding surface into which the refrigerant flows through the refrigerant guide grooves; and discharge ports in the connecting groove. Each of the refrigerant discharge ports is formed at a part of the connecting groove apart from the connecting points between the connecting groove and the refrigerant guide grooves.

Abstract: A lower mold includes: refrigerant ejection ports in its press-molding surface; and three or more independent refrigerant guide grooves extending in the press-molding surface from the refrigerant ejection ports to guide the refrigerant ejected from the refrigerant ejection port to an outer portion of the press-molding surface with the refrigerant being in contact with a workpiece. Each of the refrigerant guide grooves neither branches halfway nor merges with the others of the refrigerant guide grooves to extend from the refrigerant ejection ports to the outer portion of the press-molding surface.

Abstract: The en-bloc heat treatment of a manganese steel product whose alloy has a carbon fraction (C) in the following range 0.02?C?0.35% by weight, and a manganese content (Mn) in the following range of 3.5% by weight?Mn?6% by weight. The en-bloc annealing method has the following substeps: heating (E1) the steel product to a first holding temperature (T1) which is in the range of 820° C.±20° C., first holding (H1) of the steel product during a first holding period (?1) at the first holding temperature (T1), faster first cooling (A1) of the steel product to a second holding temperature (T2) which is in the range between 350° C. and 450° C., second holding (H2) of the steel product during a second holding period (?2) in the range of the second holding temperature (T2), performing a slower second cooling (A2).

Abstract: Provided is a hot-dip galvanized steel plate which is applicable as a material for a vehicle outer panel and has an excellent bake hardenability and anti-aging property at room temperature, and a method for manufacturing a hot-dip galvanized steel plate, the method comprising a process including the steps of: winding a hot-rolled steel plate, followed by cooling at a speed of 0.002-0.027° C./sec; cold-rolling the cooled steel plate; continuously annealing the cold-rolled steel plate; and cooling the annealed steel plate in the multi-stage manner of primary to third rounds.

Abstract: A steel sheet includes a predetermined chemical composition and a metal structure represented by, in area fraction, ferrite: 30% to 50%, granular bainite: 5% to 20%, martensite: 30% to 55%, bainite: less than 35%, and retained austenite and pearlite: 10% or less in total. Preferably, of the steel sheet, a tensile strength is 1180 MPa or more, elongation is 10% or more, and a hole expansion value is 20% or more. Further preferably, a VDA bending angle in the case where a thickness is set to t (mm) is “7.69t2?38.4t+109” or more.

Abstract: A cooling apparatus for a hot stamping die is configured such that a refrigerant in a two-phase coexisting state of a liquid phase and a gas phase is supplied to a cooling channel formed in the hot stamping die to cool the hot stamping die using latent heat of the refrigerant. The refrigerant maintains a constant temperature in the cooling channel of the hot stamping die, which ensures uniform cooling of the hot stamping die.

Abstract: Disclosed is, as a high-strength steel plate of API X80 grade or higher with a thickness of 38 mm or more, a thick steel plate for structural pipes or tubes that exhibits high strength in the rolling direction, excellent Charpy properties at its mid-thickness part, and high material homogeneity without addition of large amounts of alloying elements. The thick steel plate for structural pipes or tubes disclosed herein has: a specific chemical composition; a microstructure mainly composed of bainite; a tensile strength of 620 MPa or more; a Charpy absorption energy vE?20° C. at ?20° C. at the mid-thickness part of 100 J or more; a variation of Vickers hardness in a plate thickness direction ?HV10,t of 50 or less; and a variation of Vickers hardness in a plate widthwise direction ?HV10,c of 50 or less.

Abstract: The present invention provides electric-resistance welded steel pipe optimal for applications such as production of shale gas which is comprised of steel having a chemical composition which contains, by mass %, respectively, C: 0.08 to 0.18%, Si: 0.01% to 0.50%, Mn: 1.30 to 2.1%, Al: 0.001 to 0.10%, Nb: 0.005 to 0.08%, and Ti: 0.005 to 0.03%, is limited to N 0.008% or less, P: 0.020% or less, and S: 0.010% or less, and has a balance of Fe and unavoidable impurities, wherein a structure at a center part of thickness is 40% to 70% by area of ferrite phase having a circle-equivalent diameter of 1.0 ?m to 10.0 ?m and a balance of a low temperature transformation phase comprising a bainite phase, and Ceq satisfies 0.32?Ceq?0.60.

Abstract: Provided are a high-strength steel sheet and a method for manufacturing the steel sheet. The high-strength steel sheet has a specified chemical composition with the balance being Fe and inevitable impurities, a microstructure including, in terms of area ratio, 25% or less of a ferrite phase, 75% or more of a bainite phase and/or a martensite phase, and 5% or less of cementite, in which, in a surface layer that is a region within 50 ?m from the surface in the thickness direction, the area ratio of a ferrite phase is 5% to 20%, and a tensile strength is 1180 MPa or more.

Abstract: A heat-treated steel sheet member having a composition including, by mass %: C: 0.05 to 0.50%; Si: 0.50 to 5.0%; Mn: 1.5 to 4.0%; P: 0.05% or less; S: 0.05% or less; N: 0.01% or less; Ti: 0.01 to 0.10%; B: 0.0005 to 0.010%; Cr: 0 to 1.0%; Ni: 0 to 2.0%; Cu; 0 to 1.0%; Mo: 0 to 1.0%; V: 0 to 1.0%; Ca: 0 to 0.01%; Al: 0 to 1.0%; Nb: 0 to 1.0%; REM: 0 to 0.1%; and the balance: Fe and impurities. The steel sheet member has a microstructure comprising mainly martensite and retained austenite of which a volume ratio is 0.2 to 1.0%, a number density of retained carbide in the steel sheet member having circle-equivalent diameters of 0.1 mm or larger is 4.0×103/mm2 or lower, a tensile strength is 1.4 GPa or higher, and a yield ratio is 0.65 or higher.

Abstract: A high-strength bolt is provided that has high strength and excellent hydrogen embrittlement resistance characteristics. A bolt according to this invention has a chemical composition consisting of, in mass %, C: 0.22 to 0.40%, Si: 0.10 to 1.50%, Mn: 0.20 to less than 0.40%, P: 0.020% or less, S: 0.020% or less, Cr: 0.70 to 1.45%, Al: 0.005 to 0.060%, Ti: 0.010 to 0.045%, B: 0.0003 to 0.0040%, N: 0.0015 to 0.0080% and O: 0.0020% or less, with a balance being Fe and impurities, and satisfying Formula (1) and Formula (2), and with the high-strength bolt having a tensile strength of 1000 to 1300 MPa. 0.50?C+Si/10+Mn/5+5Cr/22?0.85??(1) Si/Mn>1.0??(2) Where, a content (mass %) of a corresponding element is substituted for each symbol of an element in Formula (1) and Formula (2).

Abstract: A mold for hot stamping is disclosed. The mold may include: a base plate configured to receive and exhaust coolant, at least one lower mold and at least one upper mold. The at least one lower mold may be mounted at a surface of the base plate, and configured to receive the coolant from the base plate. The lower mold may also have the same shape as a lower shape of a product so as to form the lower shape of the product during hot stamping. The upper mold is made of material different from that of the lower mold, coupled to an upper portion of the lower mold, has the same shape as an upper shape of the product so as to form the upper shape of the product, and is configured to receive the coolant from the lower mold such that the coolant flows in the upper mold.

Abstract: The present disclosure relates to a cast steel for construction equipment bucket parts and parts for a construction equipment bucket manufactured by using the same, and the cast steel includes 0.27 to 0.34 wt % of carbon (C), 1.2 to 1.8 wt % of chromium (Cr), 0.8 to 1.7 wt % of silicon (Si), 1.0 to 1.4 wt % of manganese (Mn), 0.2 to 0.4 wt % of molybdenum (Mo), 0.2 to 0.4 wt % of nickel (Ni), and a balance of iron and impurities.

Abstract: A steel composition and method from making a dual phase steel therefrom. The dual phase steel may have carbon of about 0.05% by weight to about 0.12 wt %; niobium of about 0.005 wt % to about 0.03 wt %; titanium of about 0.005 wt % to about 0.02 wt %; nitrogen of about 0.001 wt % to about 0.01 wt %; silicon of about 0.01 wt % to about 0.5 wt %; manganese of about 0.5 wt % to about 2.0 wt %; and a total of molybdenum, chromium, vanadium and copper less than about 0.15 wt %. The steel may have a first phase consisting of ferrite and a second phase having one or more of carbide, pearlite, martensite, lower bainite, granular bainite, upper bainite, and degenerate upper bainite. A solute carbon content in the first phase may be about 0.01 wt % or less.

Abstract: The invention relates to a hot-rolled steel sheet having a tensile strength of greater than 1200 MPa, an Re/Rm ratio of less than 0.75 and an elongation at break of greater than 10%, the composition of which contains, the contents being expressed by weight: 0.10%?C?0.25%; 1%?Mn?3%; Al?0.015%; Si?1.985%; Mo?0.30%; Cr?1.5%; S?0.015%; P?0.1%; Co?1.5%; B?0.005%; it being understood that 1%?Si+Al?2%; Cr+(3×Mo)?0.3%, 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% bainite, residual austenite in an amount equal to or greater than 5% and martensite in an amount equal to or greater than 2%.

Abstract: Provided is a hot-press molded article that can achieve a high level of balance between high strength and extension by region and has a region corresponding to an energy absorption site and a shock resistant site within a single molded article without applying a welding method by means of having first region having a metal structure containing both 80-97 area % of martensite and 3-20 area % of residual austenite, the remaining structure comprising no more than 5 area %, and a second region having a metal structure comprising 30-80 area % of ferrite, less than 30 area % (exclusive of 0 area %) of bainitic ferrite, no greater than 30 area % (exclusive of 0 area %) of martensite, and 3-20 area % of residual austenite.

Abstract: A mold material having a material hardness higher than 340 HB and a fine-grain structure. The mold material having a composition in weight percent that includes: C=0.25-0.35 Si=0.04-0.20 Mn=1.00-2.00 Cr=1.00-2.00 Ni=0.30-less than 0.90 Mo=0.30-0.80 V=less than/equal to 0.20 Al=0.01-0.03 N=0.0025-0.0150 S=less than 0.15 a remainder of Fe and impurities.

Abstract: In a method of making a motor vehicle body structure, at least one region of a sheet metal plate of hardenable steel sheet is pierced using a blanking and/or cutting process. The at least one region of the sheet metal plate is preformed into a preform which is then hot formed in a hot forming tool and press hardened.

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 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: A forging heat resistant steel of an embodiment contains in percent by mass C: 0.05-0.2, Si: 0.01-0.1, Mn: 0.01-0.15, Ni: 0.05-1, Cr: 8 or more and less than 10, Mo: 0.05-1, V: 0.05-0.3, Co: 1-5, W: 1-2.2, N: 0.01 or more and less than 0.015, Nb: 0.01-0.15, B: 0.003-0.03, and a remainder comprising Fe and unavoidable impurities.

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: 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: In a press-hardening plant, a contact-cooling press (12) is provided between the furnace (11) and the press-hardening press (13). Preselected parts of the blank (18) are contact-cooled such that corresponding parts of the finished product are softer and display a lower yield point.

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: Provided is a manufacturing method of a hot-rolled steel sheet which enables manufacturing of a hot-rolled steel sheet having excellent surface properties and a fine structure. The manufacturing method of a hot-rolled steel sheet uses a heating device, descaling device, row of finishing mills, cooling device disposed in the row of finishing mills, and rapid cooling device disposed immediately after the row of finishing mills, and the operations of the heating device, cooling device and rapid cooling device are controlled, thereby controlling a temperature T1 of the material to be rolled on an entry side of the row of finishing mills, a temperature T2 of the material to be rolled on an entry side of a final stand in the row of finishing mills, and a temperature T3 of the material to be rolled on an exit side of the rapid cooling device.

Abstract: A method for producing partially hardened steel components in which a blank composed of a hardenable sheet steel is subjected to a temperature increase and shaped into a component; the component is transferred to a tool in which the heated component is cooled and thus quench hardened; during the heating of the blank or component in order to achieve the temperature increase to a temperature required for the hardening in regions that are to have a lower hardness and/or higher ductility, cooling elements are spaced apart from the surface by a small gap; the cooling element is dimensioned so that the thermal energy acting on the region that remains ductile flows through the component into the cooling element, characterized in that in order to space the cooling element apart from the component, micro-nubs or knobs are used, which are distributed over the area of the cooling element.

Abstract: In a first step of the method of achieving TRIP microstructure in steels by deformation heat, steel feedstock is heated to a temperature below the temperature at which austenite begins to form in the steel in question, i.e. below AC1. In a next step, the feedstock is formed into a final product, using applied severe plastic deformation whereby deformation energy causes the temperature of the material to increase to the final temperature between AC1 and AC3, and whereupon the ferrite-pearlite microstructure transforms into austenite. In a third or last process step, the final product is cooled down from the final temperature to the temperature of the bainite nose of the material (B). The cooling is then interrupted and the material is held at the temperature of the bainite nose (B). Consequently, the TRIP microstructure forms. Finally, the product is cooled down to ambient temperature.

Abstract: Process for manufacturing seamless precision steel tubes with improved isotropic toughness at low temperature for hydraulic cylinders comprising the following steps; —(i) providing a steel having a composition comprising 0.06-0.15% by weight of carbon, 0.30-2.5% by weight of Mn, and 0.10-0.

Abstract: A steel material which is suitable for hot press working or hot three-dimensional bending and direct quench and which can be used to manufacture a high-strength formed article with sufficient quench hardening even by short time heating at a low temperature has a chemical composition comprising, in mass percent, C: 0.05-0.35%, Si: at most 0.5%, Mn: 0.5-2.5%, P: at most 0.03%, S: at most 0.01%, sol. Al: at most 0.1%, N: at most 0.01%, and optionally at least one element selected from the group consisting of B: 0.0001-0.005%, Ti: 0.01-0.1%, Cr: 0.18-0.5%, Nb: 0.03-0.1%, Ni: 0.18-1.0%, and Mo: 0.03-0.5% and has a steel structure in which the spheroidization ratio of carbides is 0.60-0.90.

Abstract: In a method to produce formed steel parts a primary steel material is provided, which (in % by weight) comprises C: 0.02-0.6%, Mn: 0.5-2.0%, Al: 0.01-0.06%, Si: max. 0.4%, Cr: max. 1.2%, P: max. 0.035%, S: max. 0.035%, and optionally one or more of the elements of the “Ti, Cu, B, Mo, Ni, N” group, with the proviso that Ti: max. 0.05%, Cu: max. 0.01%, B: 0.0008-0.005%, Mo: max. 0.3%, Ni: max. 0.4%, N: max. 0.01%, and the remainder as iron and unavoidable impurities. The primary material is heated through at a heating temperature (TA) lying between the Ac1 and the Ac3 temperature, such that at best incomplete austenitising of the primary material takes place, is placed into a press-form tool and formed therein into the formed steel part. The formed steel part is then heated to a bainite forming temperature (TB), which is above the martensite starting temperature (MS), however below the pearlite transformation temperature of the steel.

Abstract: A method of production of high-strength hollow bodies from multiphase martensitic steels includes a heating process, a forming process and a cooling process. A heating device heats hollow steel stock to the austenitic temperature of the material from which the stock is made. The stock is then converted by deformation in a forming device into a hollow body having the final shape. A cooling device thereafter cools the hollow body such that the material with the original austenite microstructure refined by deformation during the forming process cools to a temperature at which incomplete transformation of austenite to martensite occurs. The retained austenite stabilization is performed in an annealing device by diffusion-based carbon partitioning within the material from which the hollow body is made. The hollow body is cooled in a cooling device to ambient temperature after stabilization.

Abstract: Improved steel compositions and methods of making the same are provided. The present disclosure provides advantageous wear resistant steel. More particularly, the present disclosure provides high manganese (Mn) steel having enhanced wear resistance, and methods for fabricating high manganese steel compositions having enhanced wear resistance. The advantageous steel compositions/components of the present disclosure improve one or more of the following properties: wear resistance, ductility, crack resistance, erosion resistance, fatigue life, surface hardness, stress corrosion resistance, fatigue resistance, and/or environmental cracking resistance. In general, the present disclosure provides high manganese steels tailored to resist wear and/or erosion.

Abstract: A steel sheet contains, in terms of percent by mass, C: 0.01 to 0.2%, Si: 2.0% or less, and Mn: 3.0% or less and has a martensite phase as dominant phase and ferrite with a grain size of 20 ?m or less as a second phase. The ferrite is contained in area ratio of 1% to 30% and the amount of solute carbon being 0.01 percent by mass of more. The steel sheet can provide a hot-rolled steel sheet suitable for automobile steel sheet, i.e., has excellent press workability and excellent strain aging property whereby the tensile strength significantly increases by heat treatment at about the same temperature as typical baking process after the press-working. Moreover, hardening of the ferrite phase improves the fatigue strength after the strain aging.

Abstract: A cold die steel excellent in the characteristic of suppressing dimensional change, which has a chemical composition in mass %: C: 0.7% or more and less than 1.6%, Si: 0.5 to 3.0%, Mn: 0.1 to 3.0%, P: less than 0.05% including 0%, S: 0.01 to 0.12%, Cr: 7.0 to 13.0%, one or two elements selected from the group consisting of Mo and W: amounts satisfying the formula (Mo+(W/2))=0.5 to 1.7%, V: less than 0.7% including 0, Ni: 0.3 to 1.5%, Cu: 0.1 to 1.0% and Al: 0.1 to 0.7%. Preferably, the die steel satisfies the formula in mass %: Ni/Al=1 to 3.7. It is preferred that the die steel also satisfies the following formula in mass %: (Cr?4.2×C)=5 or less and (Cr?6.3×C)=1.4 or more and that it contains 0.3% or less of Nb.

Abstract: A high-tensile-strength hot-rolled steel sheet is provided having a composition which contains 0.02 to 0.08% C, 0.01 to 0.10% Nb, 0.001 to 0.05% Ti and Fe and unavoidable impurities as a balance, wherein the steel sheet contains C, Ti and Nb in such a manner that (Ti+(Nb/2))/C<4 is satisfied, and the steel sheet has a structure where a primary phase of the structure at a position 1 mm away from a surface in a sheet thickness direction is one selected from a group consisting of a ferrite phase, tempered martensite and a mixture structure of a ferrite phase and tempered martensite, a primary phase of the structure at a sheet thickness center position is formed of a ferrite phase, and a difference ?V between a structural fraction (volume %) of a secondary phase at the position 1 mm away from the surface in the sheet thickness direction and a structural fraction (volume %) of a secondary phase at the sheet thickness center position is 2% or less.

Abstract: According to the method of production of a steel sheet pressed part with locally modified properties, the steel sheet blank is first heated in a device for heating to the austenitic temperature of the material. Next, the steel sheet blank is converted in a tool for deep drawing by deformation into a final drawn part. Subsequently, the final drawn part is cooled inside the tool for deep drawing. Various locations of the final drawn part are cooled to various temperatures and/or at various rates during the cooling process. Thereafter, the drawn part is placed in an annealing device, where retained austenite stabilization occurs by diffusion-based carbon partitioning within the material from which the drawn part is made. After stabilization, the final drawn part is removed from the annealing device and air cooled to ambient temperature.

Abstract: Provided is a low yield ratio, high strength and high toughness steel plate having excellent strain ageing resistance equivalent to API 5L X70 Grade or lower and a method for manufacturing the same. The steel plate has a metallographic microstructure that is a three-phase microstructure including bainite, M-A constituent, and quasi-polygonal ferrite, the area fraction of the bainite being 5% to 70%, the area fraction of the M-A constituent being 3% to 20%, the remainder being the quasi-polygonal ferrite, the equivalent circle diameter of the M-A constituent being 3.0 ?m or less. The steel plate has a yield ratio of 85% or less and a Charpy impact test absorbed energy of 200 J or more at ?30° C. before or after being subjected to strain ageing treatment at a temperature of 250° C. or lower for 30 minutes or less.

Abstract: The present invention provides a high-strength steel plate having excellent resistance to cutting crack, excellent Charpy absorbed energy, excellent DWTT properties, a low yield ratio, and a tensile strength of 900 MPa or more, a method of producing the steel plate, and a high-strength steel pipe using the steel plate. As solving means, a steel plate contains, by % by mass, 0.03 to 0.12% of C, 0.01 to 0.5% of Si, 1.5 to 3% of Mn, 0.01 to 0.08% of Al, 0.01 to 0.08% of Nb, 0.005 to 0.025% of Ti, 0.001 to 0.01% of N, and at least one component of 0.01 to 2% of Cu, 0.01 to 3% of Ni, 0.01 to 1% of Cr, 0.01 to 1% of Mo, and 0.01 to 0.1% of V; wherein the contents of Ca, O, and S satisfy the equation below; the microstructure includes ferrite and a second hard phase, the area fraction of ferrite being 10 to 50%; cementite in the second phase has an average grin size of 0.5 ?m or less; and the total amount of Nb and the like contained in carbides thereof present in steel is 10% or less of the total content in steel.

Abstract: A martensitic stainless steel for inexpensive seamless pipe having 655 MPa yield strength, high toughness and excellent corrosion resistance in high CO2 environments, and a method for manufacturing thereof is provided. The steel comprises C: 0.005-0.05%, Si: 0.1-0.5%, Mn: 0.1-2.0%, P: ?0.05%, S: ?0.005%, Cr: 10.0-12.5%, Mo: 0.1-0.5%, Ni: 1.5-3.0%, N: ?0.02%, Al: 0.01-0.1%, by weight, while FI value defined by the formula [FI=Cr+Mo?Ni?30(C+N)] being 5.00 to 8.49, and balance of substantially Fe. The method comprises the steps of reheating the cooled steel at temperatures from 780° C. to 960° C., quenching the reheated steel, and then tempering the quenched steel at temperatures from 550° C. to 650° C.

Abstract: To establish a method for obtaining a hot-press-formed steel member, which exhibits high strength, high tensile elongation (ductility) and high bendability, thereby having excellent deformation characteristics at the time of collision crush (crashworthiness), and which is capable of ensuring excellent delayed fracture resistance. A method for producing a hot-press-formed steel member by heating a steel sheet, which has a chemical component composition containing 0.10% (% by mass, and hereinafter the same shall apply) to 0.30% (inclusive) of C, 1.0% to 2.5% (inclusive) of Si, 1.0% to 3.0% (inclusive) of Si and Al in total and 1.5% to 3.0% (inclusive) of Mn, with the balance consisting of iron and unavoidable impurities, and hot press forming the steel sheet one or more times.

Abstract: A method for hot rolling a metal strip or metal sheet, wherein 1.a) the slab or the strip or sheet is subjected in a first step to one or more reshaping actions in a hot rolling mill for producing a uniform, fine, recrystallised austenite structure and 2) the slab or the strip or sheet is then subjected in a second step to cooling for producing a fine-grain structure. The slab or the strip or sheet is subjected to heating between at least two roll stands of the hot rolling mill during performance of the step 1.a). The roll stands are arranged to follow one another in a rolling direction and in each of which the slab or the strip or sheet is subjected to reshaping. A heater for heating the rolling stock is arranged between at least two of the roll stands.

Abstract: There is provided a rolled steel with excellent toughness, a drawn wire rod prepared by drawing the rolled steel, and a method for manufacturing the same, in which even if a heating step is omitted, the toughness of the steel can be improved by securing a degenerated pearlite structure in an internal structure of the rolled steel by controlling a content of Mn among components and cooling conditions, and then preventing C diffusion. The rolled steel according to the present invention includes C: 0.15˜0.30%, Si: 0.1˜0.2%, Mn: 1.8˜3.0%, P: 0.035% or less, S: 0.040% or less, the remainder Fe, and other inevitable impurites, as a percentage of weight, in which the microstucture of the rolled steel is composed of ferrite and pearlite including cementite with 150 nm or less of thickness.

Abstract: The present invention provides high temperature strength and fire-resistant steel superior in weld joint reheat embrittlement resistance and toughness which is produced using steel of a room temperature strength of the 400 to 600N/mm2 class containing as main ingredients C: 0.010% to less than 0.05%, Si: 0.01 to 0.50%, Mn: 0.80 to 2.00%, Cr: 0.50% to less than 2.00%, V: 0.03 to 0.30%, Nb: 0.01 to 0.10%, N: 0.001 to 0.010%, and Al: 0.005 to 0.10%, limiting the contents of Ni, Cu, Mo, and B, and satisfying the relationship of 4Cr[%]-5Mo[%]-10Ni[%]-2Cu[%]-Mn[%]>0.

Abstract: A high-strength hot-rolled steel sheet has a tensile strength (TS) of 540 to 780 MPa, only small variations in strength, and excellent uniformity in strength using a general-purpose Ti-containing steel sheet, which is inexpensive. The high-strength hot-rolled steel sheet includes, on a mass percent basis, 0.05%-0.12% C, 0.5% or less Si, 0.8%-1.8% Mn, 0.030% or less P, 0.01% or less S, 0.005%-0.1% Al, 0.01% or less N, 0.030%-0.080% Ti, and the balance being Fe and incidental impurities. The microstructure have a bainitic ferrite fraction of 70% or more, and the amount of Ti present in a precipitate having a size of less than 20 nm is 50% or more of the value of Ti* calculated using formula (1): Ti*=[Ti]?48/14×[N] (1) where [Ti] and [N] represent a Ti content (percent by mass) and a N content (percent by mass), respectively, of the steel sheet.

Abstract: A carbon steel sheet having high formability due to a microscopic and uniform carbide distribution and having a good characteristic of final heat treatment, and a manufacturing method thereof. The carbon steel sheet having excellent formability includes, in wt %, C at 0.2-0.5%, Mn at 0.1-1.2%, Si at less than or equal to 0.4%, Cr at less than or equal to 0.5%, Al at 0.01-0.1%, S at less than or equal to 0.012%, Ti at less than or equal to 0.5×48/14×[N]% to 0.03% when the condition of B and N is not satisfied, B at 0.0005-0.0080%, N at less than or equal to 0.006%, Fe, and extra inevitable elements; an average size of carbide is less than or equal to 1 ?m; and an average grain size of ferrite is less than or equal to 5 ?m.

Abstract: Disclosed are heat-hardened steel with excellent crashworthiness and a method for manufacturing heat-hardenable parts using the same. The heat-hardened steel according to the invention comprises, based on wt %; C: 0.12-0.8%; Cr: 0.01-2%; Mo: 0.2% or less; B: 0.0005-0.08%; Ca: 0.01 or less; Sb: 1.0% or less; and Ti and/or Nb: 0.2%; and the reminder being Fe and inevitable impurities. In addition, the heat-treatment hardening steel satisfies anyone of following conditions i)-iv), wherein condition i) comprises Si: 0.5-3%; Mn: 1-10% and Al: 0.05-2%; condition ii) comprises Si: 1% or less; Mn: 0.5-5%; Al: 0.1-2.5%; and Ni: 0.01-8%; condition iii) comprises Si: 0.5-3%; Mn: 1-10%; Al: 0.1% or less; and Ni: 0.01-8%; and condition iv) comprises Si: 0.5-3%; Mn: 1-10%; Al: 0.1-2.5%; and Ni: 0.01-8%.

Abstract: A flat steel product which is provided for forming into a component by hot pressing and which has a base layer of steel on which is applied a Zn or a Zn alloy metallic protective coating for protecting against corrosion. On at least one of the free surfaces of the flat steel product, a separate cover layer is applied which contains an oxide, nitride, sulphide, carbide, hydrate or phosphate compound of a base metal. In addition, a method which allows the production of such a flat steel product, and a method which allows the production of a component from such a flat steel product.