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 consisting of 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: Provided are a cold-rolled steel sheet which undergoes a small load at the time of cold-rolling, has excellent press formability and high strength, and a method of manufacturing the cold-rolled steel sheet. A hot-rolled steel sheet having the composition comprising by mass %, 0.10 to 0.30 C, 0.2 or more Mn, 0.01 or more Ni, 0.5 to 2.5 Mn+Ni, 1.2 to 9.0 Cr, and Fe and unavoidable impurities as a balance, and has a tensile strength of 1000 MPa or less is subjected to pickling and, is subjected to cold rolling at a total rolling reduction of 60% or more thus forming a cold-rolled steel sheet. A final continuous annealing treatment is performed at a soaking temperature of 750° C. or above and at a cooling rate of 3° C./s to 100° C./s so that the cold-rolled steel sheet which has a tensile strength of 1280 MPa or more, breaking elongation of 3% or more, and a thickness of 0.05 to 0.60 mm is manufactured.

Abstract: The present invention relates to a method of manufacturing ultra-high strength steel products and, more particularly, to a method of manufacturing ultra-high strength steel products suitable for production of articles having a complicated shape or a high processing depth. The method includes preparing a steel sheet by blanking the steel sheet having hardenability to form a rough shape of a final product, cold-pressing the steel sheet to form a 50˜80% shape of the final product, precisely trimming the cold-formed steel sheet along a contour line corresponding to an outer contour of the final product, and hot-pressing the trimmed product to form the remaining 20˜50% shape of the final product and quenching simultaneous with hot-pressing, after heating the trimmed product to an austenite region of 700° C. or more.

Abstract: The present invention, among other things, relates to a method for producing a workpiece by press hardening a semi-finished product, which is distinguished by the fact that the semi-finished product consists of a steel which has a high content of silicon of at least 0.9 wt. %, with a simultaneously small content of manganese of less than 0.9 wt. %, a small carbon content of less than 0.25 wt. %, and a high chromium content of more than 1.20 wt. %, and which by heating is brought to a state in which the structure of the steel that is used is at least partially transformed to austenite, also optionally fully transformed to austenite, and the thus-heated semi-finished product is hot shaped so that after the hot deformation shaping, a structure is present in the workpiece that has a complex phase structure with predominantly martensite and ferrite fractions. In addition, a workpiece is described, which is produced according to this method, as well as uses of such a workpiece.

Abstract: A high-tensile steel plate of low acoustic anisotropy and high weldability having yield stress of 450 MPa or greater and tensile strength of 570 MPa or greater and a process for producing the steel plate are provided. The steel has an Si content of 0.10% or less, thereby achieving a volume ratio of island martensite of 3% or less, contains Nb?0.025% and Ti?0.005% so as to satisfy 0.045%?[Nb]+2×[Ti]?0.105%, contains Nb, Ti, C and N in ranges such that the value of A=([Nb]+2×[Ti])×([C]+[N]×12/14) is 0.0022 to 0.0055, and has a steel structure wherein bainite volume ratio is 30% or more and pearlite volume ratio is less than 5%.

Abstract: Steel for induction hardening wherein coarsening of austenite crystal grains can be prevented even at a high temperature of over 1100° C. such as which occurs at projecting parts of steel parts at the time of induction hardening, the steel for induction hardening characterized by containing, by mass %, C: 0.35 to 0.6%, Si: 0.01 to 1%, Mn: 0.2 to 1.8%, S: 0.001 to 0.15%, Al: 0.001 to 1%, Ti: 0.05 to 0.2%, and Nb: 0.001 to 0.04%, restricting N: 0.0060% or less, P: 0.025% or less, and O: 0.0025% or less, satisfying Nb/Ti?0.015, and having a balance of iron and unavoidable impurities.

Abstract: A high strength steel sheet has a tensile strength of 980 MPa or higher includes a composition including, on a mass% basis, C: 0.1% or more and 0.3% or less, Si: 2.0% or less, Mn: 0.5% or more and 3.0% or less, P: 0.1% or less, S: 0.07% or less, Al: 1.0% or less, and N: 0.008% or less, with the balance being Fe and incidental impurities, wherein a steel micro-structure includes, on an area ratio basis, martensite: 50% or more, ferrite: 50% or less, bainite: 10% or less, and retained austenite: 10% or less; and the full-width at half maximum in a frequency distribution of nano-hardness, which is obtained by measuring a hardness distribution of the martensite, is 2.0 GPa or more.

Abstract: A high-strength steel plate includes the following composition: 0.18 to 0.23 mass % of C; 0.1 to 0.5 mass % of Si; 1.0 to 2.0 mass % of Mn; 0.020 mass % or less of P; 0.010 mass % or less of S; 0.5 to 3.0 mass % of Ni; 0.003 to 0.10 mass % of Nb; 0.05 to 0.15 mass % of Al; 0.0003 to 0.0030 mass % of B; 0.006 mass % or less of N; and a balance composed of Fe and inevitable impurities. A weld crack sensitivity index Pcm of the high-strength steel plate is 0.36 mass % or less. The Ac3 transformation point is equal to or less than 830° C., the percentage value of a martensite structure is equal to or greater than 90%, the yield strength is equal to or greater than 1300 MPa, and the tensile strength is equal to or greater than 1400 MPa and equal to or less than 1650 MPa. A prior austenite grain size number N? is calculated by N?=?3+log2m using an average number m of crystal grains per 1 mm2 in a cross section of a sample piece of the high-strength steel plate.

Abstract: The invention relates to an air hardenable high-hardness steel for armouring applications, such as armour plate for use in light armoured vehicles and body armour, and having a high level of ballistic performance relative to its plate thickness. In particular, the invention concerns a high ballistic strength martensitic armour steel which, in an air cooled and untempered condition, has a strength coefficient (s0) of higher than 2500 MPa; a flow parameter (P) of higher than 8.0, preferably higher than 18.0; and a manganese content of 1.8 to 3.6% by weight of manganese, preferably 2.8 to 3.1% by weight of manganese. The armour steel also includes retained austenite at a volume fraction of at least 1%, and preferably a volume fraction of 4 to 20%.

Abstract: It is an object of the present invention to provide a high strength cold-rolled steel sheet, which has superior bake hardenability, aging resistance at room temperature and secondary work embrittlement resistance, and a method for manufacturing the same. The steel sheet has a grain size of ASTM No. of 9 or more after annealing, a BH of 30 MPa or more, an AI of 30 MPa or less, and a tensile strength of 340˜390 MPa through appropriate control of solute elements in steel by addition of a small amount of Ti, addition of Al and Mo, and control of manufacturing conditions, and refinement of crystal grains after annealing. The cold-rolled steel sheet and the galvannealed steel sheet produced using the cold-rolled steel sheet have the superior bake hardenability, aging resistance at room temperature, and secondary work embrittlement resistance.

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: 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 a very thin steel sheet and production method thereof that, in a very thin steel sheet of 0.4 mm or less thickness, enable production at low addition of special elements, simultaneous achievement of both good workability and anti-aging property, and stable passing of even wide coil in a continuous annealing process, which very thin steel sheet and production method.

Abstract: A method and device for controlled straightening and cooling of a wide metal strip, especially a steel strip or sheet metal, running out of a hot rolled strip rolling mill, using pinching rollers arranged in the moving direction of the strip behind vertical double rollers, said pinching rollers producing a tensile stress acting in a longitudinal direction. According to the invention, the range of use of conventional sheet metal cooling systems can be extended to obtain a more even surface of said steel strip with an increased cooling effect. This is achieved by displacing the metal strip or sheet metal between a pre-straightening machine and splash cooling facility in defined conditions of tensile stress by adjusting the tensile stress and by cooling said strip or sheet metal inside said splash cooling facility between successive pairs of pinching rollers and by additionally controlling the tensile stress.

Abstract: An APIX100-grade high strength steel pipe includes a base material containing, in mass percentage, C: more than 0.03% and 0.08% or less, Si: 0.01% to 0.5%, Mn: 1.5% to 3.0%, P: 0.015% or less, S: 0.005% or less, Al: 0.01% to 0.08%, Nb: 0.005% to 0.025%, Ti: 0.005% to 0.025%, N: 0.001% to 0.010%, O: 0.005% or less, and B: 0.0003% to 0.0020%, further contains one or more of Cu, Ni, Cr, Mo, and V, satisfies 0.19?Pcm?0.25, the balance being Fe and unavoidable impurities, and has a TS of 760 to 930 MPa, a uniform elongation of 5% or more, and a YR of 85% or less; the seam weld metal has a specific composition.

Abstract: It is provided a steel sheet heating device that heats a flat steel sheet, including: a hot plate having a flat heating surface brought into close contact with the steel sheet; and a plurality of heating equipment able to heat a plurality of heating regions, formed by dividing the heating surface of the hot plate into a plurality of sections, to different heating temperatures at the same time, wherein the steel sheet is heated to different temperatures at various portions based on the heating temperatures of the plurality of heating regions of the heating surface, at the same time through a single heating treatment.

Abstract: The present invention provides high strength thick-gauge steel plate superior in weldability and having a tensile strength of 780 MPa or more and provides a method of production of the high strength thick-gauge steel plate by omitting tempering heat treatment in the production. The high strength thick-gauge steel plate of the present invention is high strength thick-gauge steel plate containing, by mass %, C: 0.030 to 0.055%, Mn: 2.4 to 3.5%, P: 0.01% or less, S: 0.0010% or less, Al: 0.06 to 0.10%, B: 0.0005 to 0.0020%, and N: 0.0015 to 0.0060%, having a weld cracking susceptibility parameter Pcm of 0.18% to 0.24%, and comprised mainly of martensite. The method of production of high strength thick-gauge steel plate of the present invention comprises heating a steel slab or cast slab having a predetermined composition of ingredients to 950 to 1100° C., rolling it at 820° C. or more, then starting accelerated cooling from 700° C. or more by a cooling rate of 8 to 80° C.

Abstract: By heating a steel material comprising C: 0.003 to 0.05%, Si: 0.60% or less, Mn: 0.6 to 2.0%, P: 0.020% or less, S: 0.010% or less, Cr: 0.20 to 1.5%, Nb: 0.005 to 0.05%, Al: 0.060% or less, and N: 0.001 to 0.006%, further limiting, as an impurity, Mo to 0.03% or less, having a balance of iron and unavoidable impurities, and having a weld cracking parameter PCM value defined by PCM=C+Si/30+Mn/20+Cu/20+Ni/60+Cr/20+Mo/15+V/10+5B of 0.22% or less, to 1000 to 1300° C. in temperature, finishing the hot rolling at 800° C. or more in temperature, then cooling, steel for welded structures excellent in high temperature strength and low temperature toughness can be inexpensively provided.

Abstract: A method for manufacturing a fine spheroidized steel sheet having an excellent heat treatment characteristic, the method including: i) manufacturing a high carbon slab that is formed of 0.3 to 1.0 wt % C, 0.1 to 1.2 wt % Mn, 0 to 0.4 wt % Si, 0.01 to 0.1 wt % Al, 0 to 0.01 wt % S, and balance Fe and an inevitably added impurity as residuals; ii) reheating the slab to a temperature of Ar3 transformation point or more; iii) roughing rolling the slab, and manufacturing a thin plate by performing finish rolling in an austenite region; iv) cooling the thin plate at a cooling speed of 50 to 300° C./sec; v) finishing the cooling of the thin plate at a temperature region of 400 to 650° C. and maintaining the temperature; vi) winding the thin plate at a temperature region of 450 to 700° C.; vii) performing cold rolling at a reduction ratio of 30% or more; and viii) spheroidizing annealing the cold rolled thin plate.

Abstract: A high-strength steel plate includes the following composition: 0.18 to 0.23 mass % of C; 0.1 to 0.5 mass % of Si; 1.0 to 2.0 mass % of Mn; 0.020 mass % or less of P; 0.010 mass % or less of S; greater than 0.5 mass % and equal to or less than 3.0 mass % of Cu, 0.25 to 2.0 mass % of Ni; 0.003 to 0.10 mass % of Nb; 0.05 to 0.15 mass % of Al; 0.0003 to 0.0030 mass % of B; 0.006 mass % or less of N; and a balance composed of Fe and inevitable impurities. A weld crack sensitivity index Pcm of the high-strength steel plate is calculated by Pcm=[C]+[Si]/30+[Mn]/20+[Cu]/20+[Ni]/60+[Cr]/20+[Mo]/15+[V]/10+5[B], and is 0.39 mass % or less. The Ac3 transformation point is equal to or less than 850° C., the percentage value of a martensite structure is equal to or greater than 90%, the yield strength is equal to or greater than 1300 MPa, and the tensile strength is equal to or greater than 1400 MPa and equal to or less than 1650 MPa.

Abstract: Disclosed are a high-strength, high-toughness hot- pressed steel plate member and a manufacturing method therefor. A specified hot-press process is performed on a steel plate member that, with respect to the chemical composition of the steel plate, includes: 0.15 to 0.4 wt % of C; 1.0 to 5.0 wt % of Mn or of a total of Mn and at least one of Cr, Mo, Cu, and Ni; 0.02 to 2.0 wt % of at least any one of Si and Al; and the remainder being Fe and unavoidable impurities, thus providing the physical properties of a martensite phase average grain diameter of 5 ?m or less and a tensile strength of 1200 MPa or higher.

Abstract: The present invention relates to a Fe—Ga—Al-based magnetostrictive thin-sheet material and a process for preparation thereof. The raw materials used for production of the thin-sheet material is composed of the components according to the general Formula, Fe100-x-y-zGaxAlyMz, wherein x=10-30, y=1-10, and z=0.1-5, and M is any one, or more elements selected from V, Cr, Zr, Sb, Sn, Ti, SiC.

Abstract: A high strength steel plate containing 0.02 to 0.08% C, by mass, and has substantially a two phase microstructure of ferrite and bainite. The ferrite contains precipitates having a particle size of 30 nm or smaller grain size. The steel plate has a yield strength of 448 MPa or higher. A method for manufacturing the high strength steel plate which comprises hot rolling, accelerated cooling and reheating. The accelerated cooling is conducted down to a temperature of 300 to 600° C. at a cooling rate of 5° C./s or higher. The reheating is conducted up to a temperature of 550 to 700° C. at a heating rate of 0.5° C./s or higher.

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

Abstract: A method continuously creates a bainite structure in a carbon steel, especially a strip steel by austenitizing the carbon steel; introducing the austenitized carbon steel into a bath containing a quenching agent; adjusting the carbon steel to the transformation temperature for bainite and maintaining the transformation temperature for a certain period of time; and then cooling the carbon steel. The carbon steel stays in the bath until a defined percentage of the bainite structure relative to the total structure of the carbon steel has formed. Residues of the quenching agent are removed from the surface of the carbon steel by blowing the same off when the carbon steel is discharged from the bath, and the remaining structure components of the carbon steel are then transformed into bainite in an isothermal tempering station without deflecting the carbon steel at all.

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

Abstract: A cold-rolled steel sheet includes, on a percent by mass basis: C: 0.0010% to 0.0030%, Si: 0.05% or less, Mn: 0.1% to 0.3%, P: 0.05% or less, S: 0.02% or less, Al: 0.02% to 0.10%, N: 0.005% or less, and Nb: 0.010% to 0.030% and the remainder composed of Fe and incidental impurities, wherein r values in a rolling direction and a direction perpendicular to the rolling direction are within a range of 1.0 to 1.6, and a mean value Elm of elongations in the rolling direction, a direction at 45° with respect to the rolling direction, and the direction perpendicular to the rolling direction is 40% or more, where Elm=(ElL+2×ElD+ElC)/4 ElL: elongation in the rolling direction, ElD: elongation in the direction at 45° with respect to the rolling direction, and ElC: elongation in the direction perpendicular to the rolling direction.

Abstract: The present invention aims at providing: a method for manufacturing such a kind of gasket-oriented steel plate excellent in elasticity and formability, in a manner to allow for reduction of a breaking elongation of the steel plate to thereby improve a formability (punchability) thereof while improving a proof stress of the steel plate against a repeated stress from a discharge valve to thereby maintain a higher elasticity of the steel plate; and a gasket able to withstand the repeated stress from the discharge valve. The manufacturing method of a gasket-oriented steel plate of the present invention comprises the steps of: annealing a starting steel material having a composition of: Mn less than 0.5%, Ni less than 2.0%, and Cr less than 12.0%; and subsequently temper rolling the annealed starting steel material at a rolling reduction ratio of 10% or more; and the gasket of the present invention is formed by adopting a gasket-oriented steel plate obtained by the above manufacturing method.

Abstract: High-strength steel of which the chemical composition comprises, by weight: 0.03%?C<0.2% Si?0.49% 3%<Mn?4% Ni?0.9% 1%?Cr?5% Mo+W/2?1% Cu?0.9% S+Se/2+Te/3<0.020% Al?0.1%, the remainder being iron and impurities resulting from production. Block and plates obtained.

Abstract: A process for reducing flatness deviations in an alloy article is disclosed. An alloy article may be heated to a first temperature at least as great as a martensitic transformation start temperature of the alloy. A mechanical force may be applied to the alloy article at the first temperature. The mechanical force may tend to inhibit flatness deviations of a surface of the alloy article. The alloy article may be cooled to a second temperature no greater than a martensitic transformation finish temperature of the alloy. The mechanical force may be maintained on the alloy article during at least a portion of the cooling of the alloy article from the first temperature to the second temperature.

Abstract: An ultra-high strength steel sheet has a tensile strength of 1400 MPa or higher that can achieve both high strength and good formability and an advantageous method for manufacturing the steel sheet and includes a composition including, on a mass basis C: 0.12% or more and 0.50% or less; Si: 2.0% or less; Mn: 1.0% or more and 5.0% or less; P: 0.1% or less; S: 0.07% or less; Al: 1.0% or less; and N: 0.008% or less, with the balance Fe and incidental impurities. The steel microstructure includes, on an area ratio basis, 80% or more of autotempered martensite, less than 5% of ferrite, 10% or less of bainite, and 5% or less of retained austenite; and the mean number of precipitated iron-based carbide grains each having a size of 5 nm or more and 0.5 ?m or less and included in the autotempered martensite is 5×104 or more per 1 mm2.

Abstract: The present invention provides high strength thick-gauge steel plate superior in weldability and having a tensile strength of 780 MPa or more and provides a method of production of the high strength thick-gauge steel plate by omitting tempering heat treatment in the production. The high strength thick-gauge steel plate of the present invention is high strength thick-gauge steel plate containing, by mass %, C: 0.030 to 0.055%, Mn: 2.4 to 3.5%, P: 0.01% or less, S: 0.0010% or less, Al: 0.06 to 0.10%, B: 0.0005 to 0.0020%, and N: 0.0015 to 0.0060%, having a weld cracking susceptibility parameter Pcm of 0.18% to 0.24%, and comprised mainly of martensite. The method of production of high strength thick-gauge steel plate of the present invention comprises heating a steel slab or cast slab having a predetermined composition of ingredients to 950 to 1100° C., rolling it at 820° C. or more, then starting accelerated cooling from 700° C. or more by a cooling rate of 8 to 80° C.

Abstract: The present invention provides a steel plate that exhibits excellent low-temperature toughness in a base material and a weld heat-affected zone and has small strength anisotropy, wherein the steel includes, by mass, C: 0.04%-0.10%; Si: 0.02%-0.40%; Mn: 0.5%-1.0%; P: 0.0010%-0.0100%; S: 0.0001%-0.0050%; Ni: 2.0%-4.5%; Cr: 0.1%-1.0%; Mo: 0.1%-0.6%; V: 0.005%-0.1%; Al: 0.01%-0.08%; and N: 0.0001%-0.0070%, with the balance including Fe and inevitable impurities, a Ni segregation ratio at a portion located at one-fourth of a thickness of the steel plate in a steel-plate thickness direction from a surface of the steel plate is 1.3 or lower, a degree of flatness of a prior austenite grain is in a range from 1.05 to 3.0, an effective diameter of crystal grain is 10 ?m or lower, and a Vickers hardness number is in a range of 265 HV to 310 HV.

Abstract: A high strength thin steel sheet that is mainly used for structural members and inner and outer panels for a vehicle, a galvanized steel sheet, and methods of manufacturing the same. The high strength thin steel sheet for superior press formability includes, by weight percent, 0.06 to 0.4% C, 1.0 to 5.0% Mn, 0.05 to 2.5% Si, 0.01 to 2.0% Ni, 0.02 to 2% Cu, 0.01 to 0.04% Ti, 0.05 to 2.5% Al, 0.005 to 0.1% Sb, 0.0005 to 0.004% B, 0.007% or less N, and balance Fe and inevitable impurities, and meeting relation of Ni+0.5×Mn+0.3×Cu>0.9, which is defined as Ni*, and Al/Ni*<1.3 at a same time, and relation of Ti?0.028×Al. This thin steel sheet is galvanized or galvannealed.

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

Abstract: The present invention provides a fire-resistant steel material superior in weld heat affected zone reheat embrittlement resistance and low temperature toughness when welded by large heat input and exposed to fire and a method of production of the same, that is, a material containing C: 0.012 to 0.050%, Mn: 0.80 to 2.00%, Cr: 0.80 to 1.90%, and Nb: 0.01 to less than 0.05%, restricting Cu to 0.10% or less, containing suitable quantities of Si, N, Ti, and Al, restricting the contents of Mo, B, P, S, and O, and having a balance of Fe and unavoidable impurities, having contents of C, Mn, Cr, Nb, and Cu satisfying ?1200C?20Mn+30Cr?330Nb?120Cu??80, having a steel structure as observed by an optical microscope of an area fraction of 80% or more of a ferrite phase, and having a balance of the steel structure of a bainite phase, martensite phase, and mixed martensite-austenite structure.

Abstract: A method produces a high-strength cold-rolled steel sheet includes hot-rolling and cold-rolling steel having a composition which contains, by % by mass, over 0.01% to less than 0.08% of C, 0.2% or less of Si, 0.8% to less than 1.7% of Mn, 0.03% or less of P, 0.02% or less of S, 0.3% or less of sol. Al, 0.01% or less of N, and over 0.4% to 2% of Cr, and which satisfies 1.9<[Mneq]<3 and 0.34?[% Cr]/[% Mn], the balance being composed of iron and inevitable impurities; heating at an average heating rate of less than 3° C./sec in a temperature range of 680° C. to 740° C.; annealing at an annealing temperature of over 740° C. to less than 820° C.; cooling at an average cooling rate of 2 to 30° C./sec in a temperature range of the annealing temperature to 650° C.; cooling at an average cooling rate of 10° C./sec or more in the temperature range of 650° C. to Tc° C.

Abstract: The present disclosure provides alloys having an ultra-low coefficient of thermal expansion in the range of 60° F. to 80° F. The alloys have coefficient of thermal expansion no greater than 0.35×10?6° F.?1 in the range of 60° F. to 80° F. Methods of making such alloys also are provided, as well articles of manufacture including such alloys and methods of making such articles.

Abstract: A rail manufacturing method is provided, in which a billet is hot-rolled into a rail form and the rail is cooled to ambient temperature. The foot part of the rail can be mechanically restrained to improve the straightness of the rail during at least the period of cooling where the surface temperature is between 800° C. and 400° C. In the subsequent cooling process, at least while the surface temperature of the foot of the rail is between 400° C. and 250° C., the rail is kept in an upright state, and cooled naturally without using insulation or accelerated cooling.

Abstract: The present invention relates to a method of manufacturing ultra-high strength steel products and, more particularly, to a method of manufacturing ultra-high strength steel products suitable for production of articles having a complicated shape or a high processing depth. The method includes preparing a steel sheet by blanking the steel sheet having hardenability to form a rough shape of a final product, cold-pressing the steel sheet to form a 50˜80% shape of the final product, precisely trimming the cold-formed steel sheet along a contour line corresponding to an outer contour of the final product, and hot-pressing the trimmed product to form the remaining 20˜50% shape of the final product and quenching simultaneous with hot-pressing, after heating the trimmed product to an austenite region of 700° C. or more.

Abstract: A high strength and low yield ratio steel that has excellent characteristics such as low temperature toughness, a tensile strength of approximately 600 MPa or more and a low yield ratio of 80% or less. The high strength and low yield ratio steel includes, by weight percent: C: 0.02 to 0.12%, Si: 0.01 to 0.8%, Mn: 0.3 to 2.5%, P: 0.02% or less, S: 0.01% or less, Al: 0.005 to 0.5%, Nb: 0.005 to 0.10%, B: 3 to 50 ppm, Ti: 0.005 to 0.1%, N: 15 to 150 ppm, Ca: 60 ppm or less, and the balance of be and inevitable impurities, and further includes at least one component selected from the group consisting of by weight percent: Cr: 0.05 to 1.0%, Mo: 0.01 to 1.0%, Ni: 0.01 to 2.0%, Cu: 0.01 to 1.0% and V: 0.005 to 0.3%, wherein a finish cooling temperature is limited to 500 to 600° C. after the finish-rolling process.

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: There is provided a high-strength steel plate having acicular ferrite and bainite as a main microstructure and an austenite/martensite (M & A) as a second phase under the control of a cooling rate above the austenite transformation temperature. The high-strength steel plate comprises: carbon (C): 0.03 to 0.10 wt %, silicon (Si): 0.1 to 0.4 wt %, manganese (Mn): 1.8 wt % or less, nickel (Ni): 1.0 wt % or less, titanium (Ti): 0.005 to 0.03 wt %, niobium (Nb): 0.02 to 0.10 wt %, aluminum (Al): 0.01 to 0.05 wt %, calcium (Ca): 0.006 wt % or less, nitrogen (N): 0.001 to 0.006 wt %, phosphorus (P): 0.02 wt % or less, sulfur (S): 0.005 wt % or less, and the balance of iron (Fe) and other inevitable impurities.

Abstract: A manufacturing method for a heavy munition casing is provided, in which steel is rolled as a rough sheet or is forged as a slab depending on the desired casing size. Steel plates (2) produced in this way have a thickness that is somewhat greater than the manufacturing diameter of the munition casing (5). The steel used for this purpose has longitudinally oriented manganese sulfides (3), which are also shaped in the lateral direction, in addition to main shaping in the longitudinal direction, by shaping to form the shaped steel plate (2), and assume a longitudinally extending plate-shape as well. The initial material for the casing (5) is taken from an approximately rectangular steel plate (2), transversely with respect to the deformation direction. The quadrilateral piece obtained in this way is then turned to be round and is mechanically processed to form the shape of the casing (5).

Abstract: There are provided a steel for deep drawing, and a method for manufacturing the steel and a high pressure container. The steel for deep drawing includes, by weight: C: 0.25 to 0.40%, Si: 0.15 to 0.40%, Mn: 0.4 to 1.0%, Al: 0.001 to 0.05%, Cr: 0.8 to 1.2%, Mo: 0.15 to 0.8%, Ni: 1.0% or less, P: 0.015% or less, S: 0.015% or less, Ca: 0.0005 to 0.002%, Ti: 0.005 to 0.025%, B: 0.0005 to 0.0020% and the balance of Fe and inevitable impurities, wherein a microstructure of the steel has a triphase structure of ferrite, bainite and martensite. The steel for deep drawing may be useful to further improve the strength without the deterioration of the toughness by adding a trace of Ti and B, compared to the conventional steels having a strength of approximately 1100 MPa.

Abstract: A high-strength steel plate includes the following composition: 0.18 to 0.23 mass % of C; 0.1 to 0.5 mass % of Si; 1.0 to 2.0 mass % of Mn; 0.020 mass % or less of P; 0.010 mass % or less of S; 0.5 to 3.0 mass % of Ni; 0.003 to 0.10 mass % of Nb; 0.05 to 0.15 mass % of Al; 0.0003 to 0.0030 mass % of B; 0.006 mass % or less of N; and a balance composed of Fe and inevitable impurities. A weld crack sensitivity index Pcm of the high-strength steel plate is 0.36 mass % or less. The Ac3 transformation point is equal to or less than 830° C., the percentage value of a martensite structure is equal to or greater than 90%, the yield strength is equal to or greater than 1300 MPa, and the tensile strength is equal to or greater than 1400 MPa and equal to or less than 1650 MPa. A prior austenite grain size number N? is calculated by N?=?3+log2m using an average number m of crystal grains per 1 mm2 in a cross section of a sample piece of the high-strength steel plate.

Abstract: A cold-rolled steel sheet having superior non-ageing properties and low planar anisotropy can be produced at low cost without decreased productivity. This cold-rolled steel sheet contains, by mass, 0.010% to 0.040% carbon, 0.02% or less silicon, 1.0% to 2.5% manganese, 0.02% or less phosphorus, 0.015% or less sulfur, 0.004% or less nitrogen, and 0.020% to 0.070% aluminum, the balance being iron and incidental impurities. The steel sheet has a microstructure including a ferrite phase and a second phase. The volume percentage of the second phase is 0.2% to less than 10%. The steel sheet has an AI of 50 MPa or less, ?0.20??r?0.20, and a thickness of 0.5 mm or less.

Abstract: The present invention relates to a high carbon steel sheet that is superior in fatigue life and a method of manufacturing the high carbon steel sheet. The high carbon steel sheet includes about 0.75 wt % to about 0.95 wt % of carbon, smaller than about 1.8 wt % of silicon, about 0.1 wt % to about 1.5 wt % of manganese, about 0.1 wt %˜1.0 wt % of chromium, smaller than about 0.02 wt % of phosphorus, smaller than about 0.02 wt % of sulfur, a residual amount of iron, and inevitable impurities. A layer interval between laminar carbides included in the high carbon steel sheet is smaller than about 0.5 ?m. The high carbon steel sheet may include a fine pearlite having a lamellar structure. The fine pearlite included in the high carbon steel sheet may have a volume percentage of larger than about 90%. A ratio of length to width of the lamellar structure may be larger than about 10:1.

Abstract: A method of production of 780 MPa class high strength steel plate excellent low temperature toughness comprising heating a steel slab of containing, by mass %, C: 0.06 to 0.15%, Si: 0.05 to 0.35%, Mn: 0.60 to 2.00%, P: 0.015% or less, S: 0.015% or less, Cu: 0.1 to 0.5%, Ni: 0.1 to 1.5%, Cr: 0.05 to 0.8%, Mo: 0.05 to 0.6%, Nb: less than 0.005%, V: 0.005 to 0.060%, Ti: less than 0.003%, Al: 0.02 to 0.10%, B: 0.0005 to 0.003%, and N: 0.002 to 0.006% to 1050° C. to 1200° C. in temperature, hot rolling ending at 870° C. or more, waiting for 10 seconds to 90 seconds, then cooling from 840° C. or more in temperature by a 5° C./s or more cooling rate to 200° C., then tempering at 450° C. to 650° C. in temperature for 20 minutes to 60 minutes.

Abstract: The present invention has as its object the production of high strength electrical steel sheet, having a high strength of a tensile strength TS of for example 500 MPa or more, having wear resistance, and having superior magnetic properties of magnetic flux density and iron loss, that is, provides a method of production of high strength electrical steel sheet containing, by mass %, C: 0.060% or less, Si: 0.2 to 6.5%, Mn: 0.05 to 3.0%, P: 0.30% or less, S or Se: 0.040% or less, Al: 2.50% or less, N: 0.020% or less, and further one or more of Cu: 0.001 to 30.0% and Nb: 0.03 to 8.