Abstract: Steel, excellent in corrosion resistance and low-temperature toughness, for a vehicle suspension spring part, includes 0.15 to 0.35% by mass of C, more than 0.6% by mass but 1.5% by mass or less of Si, 1 to 3% by mass of Mn, 0.3 to 0.8% by mass of Cr, 0.005 to 0.080% by mass of sol. Al, 0.005 to 0.060% by mass of Ti, 0.005 to 0.060% by mass of Nb, not more than 150 ppm of N, not more than 0.035% by mass of P, not more than 0.035% by mass of S, 0.01 to 1.00% by mass of Cu, and 0.01 to 1.00% by mass of Ni, the balance consisting of Fe and unavoidable impurities, with Ti+Nb?0.07% by mass. The steel has a tensile strength of not less than 1,300 MPa.

Abstract: This hot-rolled steel sheet contains, in terms of mass %, C: 0.015% or more to less than 0.040%; Si: less than 0.05%; Mn: 0.9% or more to 1.8% or less; P: less than 0.02%; S: less than 0.01%; Al: less than 0.1%; N: less than 0.006%; and Ti: 0.05% or more to less than 0.11%, with the remainder being Fe and inevitable impurities, wherein Ti/C is in a range of 2.5 or more to less than 3.5, Nb, Zr, V, Cr, Mo, B and W are not included, a microstructure includes a mixed microstructure of polygonal ferrite and quasi-polygonal ferrite in a proportion of greater than 96%, a maximum tensile strength is 520 MPa or more and less than 720 MPa, an aging index AI is more than 15 MPa, a product of a hole expansion ratio (?) % and a total elongation (El) % is 2350 or more, and a fatigue limit is 200 MPa or more.

Abstract: A bainitic steel with simultaneous high yield strength and high fracture toughness includes at least 5 volume percent austenite as well as iron, carbon, and silicon. The silicon is present in an amount of at least 1.5 weight percent of total weight of the bainitic steel. A method of forming the steel by austempering is also provided.

Abstract: A high strength galvanized steel sheet has a TS of 590 MPa or more and excellent processability. The component composition contains, by mass %, C: 0.05% to 0.3%, Si: 0.7% to 2.7%, Mn: 0.5% to 2.8%, P: 0.1% or lower, S: 0.01% or lower, Al: 0.1% or lower, and N: 0.008% or lower, and the balance: Fe or inevitable impurities. The microstructure contains, in terms of area ratio, ferrite phases: 30% to 90%, bainite phases: 3% to 30%, and martensite phases: 5% to 40%, in which, among the martensite phases, martensite phases having an aspect ratio of 3 or more are present in a proportion of 30% or more.

Abstract: A high strength steel sheet including, by mass, C: 0.03% or more and 0.25% or less, Si: 0.4% or more and 2.5% or less, Mn: 3.5% or more and 10.0% or less, P: 0.1% or less, S: 0.01% or less, Al: 0.01% or more and 2.5% or less, N: 0.008% or less, Si+Al: 1.0% or more, the balance being Fe and inevitable impurities. The area ratio of ferrite is 30% or more and 80% or less, the area ratio of martensite is 0% or more and 17% or less, the volume fraction of retained austenite is 8% or more, and the average grain size of retained austenite is 2 ?m or less.

Abstract: Provided are: a high-strength steel sheet which is improved in both elongation and local formability and thus exhibits excellent workability; and a manufacturing method thereof. The high-strength steel sheet contains C, Si, Mn, Al, P and S with the remainder including iron and unavoidable impurities, and has a metal structure which includes polygonal ferrite, bainite, tempered martensite, and retained austenite. In the metal structure, (1) the bainite has a composite microstructure including both a high-temperature-formed bainite having an average distance between adjacent regions of retained austenite and/or carbide of 1 ?m or more and a low-temperature-formed bainite having an average distance between adjacent regions of retained austenite and/or carbide of less than 1 ?m each identified upon observation with a scanning electron microscope; and (2) the retained austenite is present in a volume percentage of 5% or more of the entire metal structure as determined by a saturation magnetization measurement.

Abstract: This high-strength cold-rolled steel sheet contains, in mass %, C: 0.02% to 0.20%; Si: 0.001% to 2.5%; Mn: 0.01% to 4.0%; P: 0.001% to 0.15%; S: 0.0005% to 0.03%; Al: 0.001% to 2.0%; N: 0.0005% to 0.01%; and O: 0.0005% to 0.01%; in which Si+Al is limited to less than 1.0%, and a balance being composed of iron and inevitable impurities, in which an area ratio of bainite in a metal structure is 95% or more, at a sheet thickness center portion being a range of ? to ? in sheet thickness from the surface of the steel sheet, an average value of pole densities of the {100}<011> to {223}<110> orientation group is 4.0 or less, and a pole density of the {332}<113> crystal orientation is 5.0 or less, and a mean volume diameter of crystal grains in the metal structure is 7 ?m or less.

Abstract: In a hot-rolled steel sheet, an average pole density of an orientation group of {100}<011> to {223}<110>, which is represented by an arithmetic average of pole density of each orientation of {100}<011>, {116}<110>, {114}<110>, {112}<110>, and {223}<110> in a center portion of a sheet thickness which is a range of the sheet thickness of ? to ? from a surface of the steel sheet, is 1.0 or more and 4.0 or less, the pole density of a crystal orientation of {332}<113> is 1.0 or more and 4.8 or less, an average grain size in a center in the sheet thickness is 10 ?M or less, and a microstructure includes, by a structural fraction, pearlite more than 6% and ferrite in the balance.

Abstract: Disclosed is a hot-rolled steel sheet including, by mass %, C:0.02% to 0.5% of C, and the sum of the content of Si and the content of Al is 1.0% to 4.0%. An average pole density of an orientation group from {100}<011> to {223}<110> is 1.0 to 6.5, and a pole density of a crystal orientation {332}<113> is 1.0 to 5.0. A microstructure includes, by of an area ratio, 2% to 30% of retained austenite, 20% to 50% of ferrite, and 10% to 60% of bainite. rC that is a Lankford value in a direction orthogonal to a rolling direction is 0.70 to 1.10, and r30 that is a Lankford value in a direction forming an angle of 30° with the rolling direction is 0.70 to 1.10.

Abstract: In a hot-rolled steel sheet, an average pole density of an orientation group {100}<011> to {223}<110>, which is represented by an arithmetic mean of pole densities of orientations {100}<011>, {116}<110>, {114}<110>, {112}<110>, and {223}<110> is 1.0 to 4.0 and a pole density of a crystal orientation {332}<113> is 1.0 to 4.8, in a thickness center portion which is a thickness range of ? to ? from the surface of the steel sheet; an average grain size in the thickness center portion is less than or equal to 10 ?m and a grain size of cementite precipitating in a grain boundary of the steel sheet is less than or equal to 2 ?m; and an average grain size of precipitates containing TiC in grains is less than or equal to 3 nm and a number density per unit volume is greater than or equal to 1×1016 grains/cm3.

Abstract: A high strength hot rolled steel sheet having excellent blanking workability is provided. The composition contains C: 0.050 to 0.15%, Si: 0.1 to 1.5%, Mn: 1.0 to 2.0%, P: 0.03% or less, S: 0.0030% or less, Al: 0.01 to 0.08%, Ti: 0.05 to 0.15%, N: 0.005% or less, and the balance being Fe and unavoidable impurities. More than 95% of the microstructure is formed of a bainite phase in terms of area fraction. Average grain diameters of the bainite phase in a region having a thickness equal to ¼ of the sheet thickness from the surface in the sheet thickness direction is 5 ?m or less in an L-direction cross section and 4 ?m or less in a C-direction cross section. The number of crystal grains extended in the rolling direction and having an aspect ratio of 5 or more is 7 or less in a sheet thickness center portion.

Abstract: A hot rolled steel sheet includes, as a chemical composition, at least one selected from Ti, REM, and Ca, and includes, as a metallographic structure, a ferrite as a primary phase, at least one of a martensite and a residual austenite as a secondary phase, and plural inclusions, wherein a total length in the rolling direction of both inclusion-cluster whose length in the rolling direction is 30 ?m or more and independent-inclusion whose length in the rolling direction is 30 ?m or more is 0 mm to 0.25 mm per 1 mm2.

Abstract: A steel sheet for obtaining a member which is excellent in fatigue characteristics equal to ordinary high strength steel sheet of the same strength even if applying the hot stamping process and a method of production of the same are provided. Steel sheet for a hot stamped member which includes composition which contains, by mass %, C: 0.15 to 0.35%, Si: 0.01 to 1.0%, Mn: 0.3 to 2.3%, Al: 0.01 to 0.5%, and a balance of Fe and unavoidable impurities, and limit the impurities to P: 0.03% or less, S: 0.02% or less, and N: 0.1% or less, wherein that a standard error of Vicker's hardness at a position of 20 ?m from the steel sheet surface in the sheet thickness direction is 20 or less. This steel sheet is produced by a recrystallization-annealing step of a first stage of heating a cold rolled steel sheet, which is obtained by hot rolling steel containing the above composition and then cold rolling it, by an average heating rate of 8 to 25° C./sec from room temperature to 600 to 700° C.

Abstract: The issue of the present invention is to provide a hot-rolled steel sheet with excellent press formability and method for producing the steel sheet, wherein the steel sheet has not only hole expandability but also stretch flanging workability by not assessing hole expandability for stretch flanging as conventional but an actual phenomena of side-bend elongation.

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<12 r+65 is satisfied.

Abstract: This is a cold-rolled steel sheet includes, by mass %, C: 0.02% to 0.4%, Si: 0.001% to 2.5%, Mn: 0.001% to 4.0%, and Al: 0.001% to 2.0%. The sum of the Si content and the Al content is 1.0% to 4.5%. An average pole density of an orientation group from {100}<011> to {223}<110> is 1.0 to 6.5, and a pole density of a crystal orientation {332}<113> is 1.0 to 5.0. A microstructure includes, by an area ratio %, 5% to 80% of ferrite, 5% to 80% of bainite, and 2% to 30% of retained austenite. In the microstructure, by an area ratio %, martensite is limited to 20% or less, pearlite is limited to 10% or less, and tempered martensite is limited to 60% or less.

Abstract: Provided are a high-strength cold-rolled steel sheet having excellent formability, excellent ductility, excellent hole expansibility, and high yield ratio and a method for producing the same. The high-strength cold-rolled steel sheet contains 0.05% to 0.15% C, 0.10% to 0.90% Si, 1.0% to 2.0% Mn, 0.005% to 0.05% P, 0.0050% or less S, 0.01% to 0.10% Al, 0.0050% or less N, and 0.010% to 0.100% Nb, which are chemical components, on a mass basis, the balance being Fe and unavoidable impurities; has a microstructure which is a multi-phase structure containing 90% or more of a ferrite phase and 0.5% to less than 5.0% of a martensite phase on a volume fraction basis, the remainder being low-temperature transformation phases; and has a yield ratio of 70% or more.

Abstract: The present invention provides a bainite-containing-type high-strength hot-rolled steel sheet. The steel sheet, containing C: greater than 0.07 to 0.2%, Si: 0.001 to 2.5%, Mn: 0.01 to 4%, P: 0.15% or less, S: 0.03% or less, N: 0.01% or less, Al: 0.001 to 2% and a balance being composed of Fe and impurities, has an average value of pole densities of the {100}<011> to {223}<110> orientation group at a sheet thickness center portion being a range of ? to ? in sheet thickness from the surface of the steel sheet is 4.0 or less, and a pole density of the {332}<113> crystal orientation is 4.8 or less, an average crystal grain diameter is 10 ?m or less and vTrs is ?20° C. or lower, and a microstructure is composed of 35% or less in a structural fraction of pro-eutectoid ferrite and a balance of a low-temperature transformation generating phase.

Abstract: The present invention provides a non-oriented electrical steel sheet at low cost that has excellent magnetic properties and mechanical properties as well as excellent quality of steel sheet. The non-oriented electrical steel sheet has a chemical composition containing, by mass %, Si: 5.0% or less, Mn: 2.0% or less, Al: 2.0% or less, and P: 0.05% or less, in a range satisfying formula (1), and furthermore, C: 0.008% or more and 0.040% or less; N: 0.003% or less, and Ti: 0.04% or less, in a range satisfying formula (2), with the balance composed of Fe and incidental impurities: 300?85[Si %]+16[Mn %]+40[Al %]+490[P %]?430??(1) 0.008?Ti*<1.2[C %]??(2), where Ti*=Ti?3.4[N %].

Abstract: Disclosed is a carburized machine part which is free from the problem of decreased strength at edge-shaped parts due to excess introduction of carbon. The machine part is produced by processing a case hardening steel of the alloy composition consisting essentially of, by weight %, C: 0.1-0.3%, Si: 0.5-3.0%, Mn: 0.3-3.0%, P: up to 0.03%, S: up to 0.03%, Cu: 0.01-1.00%, Ni: 0.01-3.00%, Cr: 0.3-1.0%, Al: up to 0.2% and N: up to 0.05% and the balance of Fe and inevitable impurities, and satisfying the following condition: [Si %]+[Ni %]+Cu %]?[Cr %]>0.5 and carburizing by vacuum carburization.

Abstract: A high-strength galvanized steel sheet contains C: 0.010% or more and 0.06% 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 0.1% or less, S: 0.01% or less, sol.Al: 0.005% or more and 0.5% or less, N: 0.01% or less, Nb: 0.010% or more and 0.090% or less, and Ti: 0.015% or more and 0.15% or less, on a mass percent basis. The Nb and C contents of the steel satisfy the relation of (Nb/93)/(C/12)<0.20. C* satisfies 0.005?C*?0.025. Ferrite constitutes 70% by area ratio or more of the steel sheet. Martensite constitutes 3% by area ratio or more of the steel sheet. C*=C?(12/93)Nb?(12/48){Ti?(48/14)N}, wherein C, Nb, Ti, and N denote the C, Nb, Ti, and N contents of the steel.

Abstract: Provided is a steel sheet for a formed member having enhanced ductility, a formed member, and a method for manufacturing the formed member, and more particularly, to a steel sheet for making a formed member having high strength and ductility such as an automotive structural member and a reinforcing member, a formed member, and a method for manufacturing the formed member. The steel sheet for a formed member has enhanced ductility, and includes, by weight %, C: 0.1% to 1.0%, Si+Al: 0.4% to 3.0%, Mn: 0.1% to 5.0%, P: 0.0001% to 0.1%, S: 0.0001% to 0.03%, N: 0.03% or less (but not 0%), and the balance of Fe and inevitable impurities. The formed member having high strength and ductility that can be used for forming an automotive structural member, a reinforcing member, etc. In addition, the formed member can be used for a heat-treatable impact resistant member.

Abstract: According to one aspect, provided is a high-strength steel sheet having superior toughness at cryogenic temperature, comprising, in weight percentage, 0.02 to 0.06% of C, 0.1 to 0.35% of Si, 1.0 to 1.6% of Mn, 0.02% or less (but not 0%) of Al, 0.7 to 2.0% of Ni, 0.4 to 0.9% of Cu, 0.003 to 0.015% of Ti, 0.003 to 0.02% of Nb, 0.01% or less of P, 0.005% or less of S, the remainder being Fe and unavoidable impurities, wherein the high-strength steel sheet satisfies the condition of [Mn]+5.4[Si]+26[Al]+32.8[Nb]<4.3 where [Mn], [Si], [Al], and [Nb] indicate contents of Mn, Si, Al, and Nb in weight percentage, respectively. The steel sheet secures toughness when used as structural steel materials for ships, offshore structures, or the like, or steel materials for tanks for storing and carrying liquefied gases, which are exposed to an extreme low temperature environment.

Abstract: An electron-beam welded joint including, by mass %, C: 0.02% to 0.1%, Si: 0.03% to 0.30%, Mn: 1.5% to 2.5%, Ti: 0.005 to 0.015%, N: 0.0020 to 0.0060%, O: 0.0010% to 0.0035%, Nb: 0% to 0.020%, V: 0% to 0.030%, Cr: 0% to 0.50%, Mo: 0% to 0.50%, Cu: 0% to 0.25%, Ni: 0% to 0.50%, B: 0% to 0.0030%, S: limited to 0.010% or less, P: limited to 0.015% or less, Al: limited to 0.004% or less, and a balance consisting of iron and unavoidable impurities, wherein an index value CeEB is 0.49% to 0.60%, a number of oxides having an equivalent circle diameter of 1.0 ?m or more is 20 pieces/mm2 or less, and a number of oxides having an equivalent circle diameter of 0.05 ?m or more and less than 0.5 ?m is 1×103 pieces/mm2 to 1×105 pieces/mm2 at a thickness center portion.

Abstract: A steel having a composition that includes C: 0.05 to 0.15%, Si: 0.2 to 1.2%, Mn: 1.0 to 2.0%, Al: 0.005 to 0.10%, N: 0.006% or less, and at least one selected from Ti: 0.03 to 0.13%, Nb: 0.02 to 0.10%, and V: 0.02 to 0.15% is subjected to rough rolling at a reduction of 80% or more and finish rolling at a finish rolling delivery temperature in the range of 800 to 950° C. The finish rolled sheet is subjected to cooling including cooling the finish rolled sheet from the finish rolling delivery temperature to a cooling end temperature in the range of 550 to 610° C. at an average cooling rate of 25° C./sec. or more and cooling the finish rolled sheet from the cooling end temperature of the previous process to a coiling temperature at an average cooling rate of 100° C./sec. or more.

Abstract: A low Ni and high N austenitic-ferritic stainless steel is disclosed. It includes an austenitic-ferritic stainless steel having high formability and punch stretchability, crevice corrosion resistance, corrosion resistance at welded part, or excellent intergranular corrosion resistance, from a stainless steel structured by mainly austenite phase and ferrite phase, and consisting essentially of 0.2% or less C, 4% or less Si, 12% or less Mn, 0.1% or less P, 0.03% or less S, 15 to 35% Cr, 3% or less Ni, and 0.05 to 0.6% N, by mass, by adjusting the percentage of the austenite phase in a range from 10 to 85%, by volume. Furthermore, it includes an austenitic-ferritic stainless steel having higher formability by adjusting the amount of (C+N) in the austenite phase to a range from 0.16 to 2% by mass.

Abstract: The present invention provides a wire rod with a composition at least including: C: 0.95-1.30 mass %; Si: 0.1-1.5 mass %; Mn: 0.1-1.0 mass %; Al: 0-0.1 mass %; Ti: 0-0.1 mass %; P: 0-0.02 mass %; S: 0-0.02 mass %; N: 10-50 ppm; O: 10-40 ppm; and a balance including Fe and inevitable impurities, wherein 97% or more of an area in a cross-section perpendicular to the longitudinal direction of the wire rod is occupied by a pearlite, and 0.5% or less of an area in a central area in the cross-section and 0.5% or less of an area in a first surface layer area in the cross-section are occupied by a pro-eutectoid cementite.

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

Abstract: The present invention provides a bake-hardenable high-strength cold-rolled steel sheet having excellent bake hardenability, cold aging resistance, and deep-drawability, and reduced planar anisotropy, containing chemical components in % by mass of: C: 0.0010% to 0.0040%, Si: 0.005% to 0.05%, Mn: 0.1% to 0.8%, P: 0.01% to 0.07%, S: 0.001% to 0.01%, Al: 0.01% to 0.08%, N: 0.0010% to 0.0050%, Nb: 0.002% to 0.020%, and Mo: 0.005% to 0.050%, a value of [Mn %]/[P %] being in the range of 1.6 to 45, where [Mn %] is an amount of Mn and [P %] is an amount of P, an amount of C in solid solution obtained from [C %]?(12/93)×[Nb %] being in the range of 0.0005% to 0.

Abstract: A steel for high-strength spring has an Ac3 transformation temperature as an indicator of the decarburization performance, which is calculated by Equation (1) below, is from 859 to 885° C., a maximum hardened diameter DI as an indicator of the hardening performance, which is calculated by Equation (2) below, is from 70 to 238 mm, and a temper hardness HRC as an indicator of the spring performance, which is calculated by Equation (3) below, is from 50 to 55. Ac3=910?203×?{square root over (C)}?15.2Ni+44.7Si+104V+31.5Mo+13.1W??(1) DI=DO×fSi×fMn×fP×fS×fCu×fNi×fCr??(2) HRC=38.99+17.48C+2.55Si?2.28Ni+2.37Cr+8.04Ti??(3) wherein, D0=8.65×?{square root over (C)}, fSi=1+0.64×% Si, fMn=1+4.10×% Mn, fP=1+2.83×% P, fS=1?0.62×% S, fCu=1+0.27×% Cu, fNi=1+0.52×% Ni, and fCr=1+2.33×% Cr.

Abstract: The present invention provides a steel material for hardening, including chemical components, by mass %, of: C: 0.15 to 0.60%; Si: 0.01 to 1.5%; Mn: 0.05 to 2.5%; P: 0.005 to 0.20%; S: 0.001 to 0.35%; Al: over 0.06 to 0.3%; and total N: 0.006 to 0.03%, with a balance including Fe and inevitable impurities including B of not more than 0.0004%, in which a hardness R at a position 5 mm away from a quenching end measured through a Jominy-type end-quenching method specified in JIS G 0561, and a calculation hardness H at a position 4.763 mm away from the quenching end satisfy the following Equation (1). H×0.948?R?H×1.

Abstract: A thin high strength steel sheet having excellent formability has a composition which includes, by mass %, 0.08 to 0.15% of C, 0.5 to 1.5% of Si, 0.5 to 1.5% of Mn, 0.01 to 0.1% of Al, and 0.005% or less of N to form a hot rolled sheet is conducted.

Abstract: Disclosed herein is a high-strength hot-rolled steel sheet which is characterized by high strength (in terms of tensile strength at 900 MPa level) and excellent combined formability expressed by balance between strength and ductility [tensile strength (TS)×total elongation (El)] and balance between strength and stretch flangeability [tensile strength (TS)×bore expanding ratio (?)]. The hot-rolled steel sheet contains C: no less than 0.02% and no more than 0.15%, Si: no less than 0.2% and no more than 2.0%, Mn: no less than 0.5% and no more than 2.5%, Al: no less than 0.02% and no more than 0.15%, Cu: no less than 1.0% and no more than 3.0%, Ni: no less than 0.5% and no more than 3.0%, and Ti: no less than 0.03% and no more than 0.5%. (% means mass %) It also has a metallographic structure in longitudinal cross section such that the sum of bainitic ferrite and granular bainitic ferrite accounts for no less than 85% by area.

Abstract: A high-strength cold rolled steel sheet having excellent deep drawability and bake hardenability, with a tensile strength ?440 MPa, an average r-value ?1.20 and a bake hardening value ?40 MPa, is obtained by subjecting a steel raw material having a chemical composition including C: 0.010-0.06 mass %, Si: more than 0C:\Users\ejensen\Desktop\!TEMP\.5 mass % but not more than 1.5 mass %, Mn: 1.0-3.0 mass %, Nb: 0.010-0.090 mass %, Ti: 0.015-0.15 mass % and satisfying (Nb/93)/(C/12)<0.20 to hot rolling, cold rolling and then to annealing including steps of heating to a temperature of 800-900° C. while a temperature region of 700-800° C. is an average heating rate <3° C./s, and soaking and thereafter cooling at a rate ?5° C./s from the soaking temperature to a cooling stop temperature ?500° C. to thereby form a microstructure including ferrite phase with an area ratio ?70% and martensite phase with an area ratio ?3%.

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: This profiled wire, of NACE grade, made of low-alloy carbon steel intended to be used in the offshore oil exploitation sector, is characterized in that it has the following chemical composition, expressed in percentages by weight of the total mass: 0.75<% C<0.95; 0.30<% Mn<0.85; Cr?0.4%; V?0.16%; Si?1.40% and preferably ?0.15%; and optionally no more than 0.06% Al, no more than 0.1% Ni and no more than 0.

Abstract: The present invention relates to a steel sheet for Vitreous enameling excellent in enameling properties (bubbling and black spot resistance, enamel adhesiveness and fish scale resistance) and workability, and a method for producing the same, and is characterized in that the steel sheet contains, in mass of, C: 0.010% or less, Mn: 0.03 to 1.3%, Si: 0.03% or less, Al: 0.02% or less, N: 0.0055% or less, P: below 0.035%, and S: over 0.025% to 0.08%; and the density change of the steel sheet from before an annealing to after an annealing at 850° C. for 20 hours, in a hydrogen atmosphere is 0.02% or more.

Abstract: A steel sheet for enameling for eliminating surface defects such as fish scale defects and having excellent formability, and provides a steel sheet for enamel having no surface defects, including: more than 0 wt % and 0.005 wt % or less of C, 0.1 to 0.5 wt % of Mn, more than 0 wt % and 0.03 wt % or less of Si, 0.05 to 0.3 wt % of Cr, more than 0 wt % and 0.03 wt % or less of Al, 0.03 to 0.1 wt % of O, more than 0 wt % and 0.03 wt % or less of P, more than 0 wt % and 0.02 wt % or less of S, more than 0 wt % and 0.015 wt % or less of Cu, more than 0 wt % and 0.005 wt % or less of N, Fe in a remaining content, and other inevitable impurities.

Abstract: A method for the production of hot-rolled steel strip comprising the following steps: providing a steel slab comprising, in weight percentages: Si: 2.5 to 3.5%, C: 0.05 to 0.1%, Mn: 0:05 to 0.1%, Als: 0.015 to 0.026%, N: 0.0050 to 0.0100%, and further comprising S and/or Se so that S+ (32/79) Se is in an amount of 0.018 to 0.030%, and optionally comprising one or more elements chosen among Sb in an amount of 0.015 to 0.035%, Cu in an amount of 0.08% to 0.25%, Sn in an amount of 0.06% to 0.15%, P in an amount of 0.005% to 0.015%, the balance being iron and unavoidable impurities, reheating said slab to a temperature between 1300° C. and 1430° C., roughing hot-rolling said slab to produce a blank having a thickness below 50 mm, finishing hot-rolling of said blank to produce a hot rolled strip in three rolling passes or more, the temperature of said blank during the first pass being above 1150° C.

Abstract: The present invention provides bearing steel, comprising a chemical composition including by mass %, C: 0.56%?[% C]?0.70%, Si: 0.15%?[% Si]<0.50%, Mn: 0.60%?[% Mn]?1.50%, Cr: 0.50%?[% Cr]?1.10%, Mo: 0.05%?[% Mo]?0.5%, P: [% P]?0.025%, S: [% S]?0.025%, Al: 0.005%?[% Al]?0.500%, O: [% O]?0.0015%, N: 0.0030%?[% N]?0.015%, and remainder as Fe and incidental impurities.

Abstract: The present invention provides steel containing manganese and nickel that is used as a structural material for a cryogenic storage container for liquefied natural gas (LNG) or the like, and a manufacturing method thereof; and more particularly, to steel having good cryogenic temperature toughness and also high strength by adding low-cost Mn instead of relatively expensive Ni at an optimized ratio, refining a microstructure through controlled rolling and cooling, and precipitating retained austenite through tempering, and a manufacturing method of the steel. To achieve the object, the technical feature of the present invention is a method of manufacturing high-strength steel with cryogenic temperature toughness. In the method, a steel slab is heated to a temperature within a range of 1,000 to 1,250° C., wherein the steel slab includes, by weight: 0.01-0.06% of carbon (C), 2.0-8.0% of manganese (Mn), 0.01-6.0% of nickel (Ni), 0.02-0.6% of molybdenum (Mo), 0.03-0.5% of silicon (Si), 0.003-0.

Abstract: A piston ring material is provided which retains excellent mechanical properties and processability, which are required of piston ring materials, and has wearing resistance and scuffing resistance, which are sliding properties required of piston rings. The piston ring material, which is for use in internal combustion engines, contains, in terms of mass %, 0.3-0.8% carbon, 0.1-3.0% silicon, 0.1-3.0% manganese, 0.01-0.3% sulfur, 0.1-2.0% chromium, and 0.05-2.0% the sum of titanium and/or zirconium, with the remainder being iron and incidental impurities. The titanium and/or zirconium contained in the piston ring material and the sulfur contained therein satisfy the following relationship. [Ti (%)+½Zr (%)]/S (%)?5.0 Preferably, the material may contain one or more members selected from up to 1.0% copper, less than 3.0% molybdenum, up to 1.0% aluminum, and less than 2.0% nickel, in terms of mass %.

Abstract: A steel sheet including 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 0.0030%, Al at 0.005 to 0.10%, N at not more than 0.005% and Ti at 0.03 to 0.13%, the balance being Fe and inevitable impurities, includes surface regions having an area fraction of bainite of less than 80% and an area fraction of a ferrite phase with a grain diameter of 2 to 15 ?m of not less than 10%, the surface regions extending from both surfaces of the steel sheet each to a depth of 1.5 to 3.0% relative to a total sheet thickness, as well as an inner region other than the surface regions having an area fraction of a bainite phase of more than 95%, and has a tensile strength of not less than 780 MPa.

Abstract: This high-strength steel sheet includes by mass percentage: 0.05 to 0.4% of C; 0.1 to 2.5% of Si; 1.0 to 3.5% of Mn; 0.001 to 0.03% of P; 0.0001 to 0.01% of S; 0.001 to 2.5% of Al; 0.0001 to 0.01% of N; 0.0001 to 0.008% of O; and a remainder composed of iron and inevitable impurities, wherein a steel sheet structure contains by volume fraction 10 to 50% of a ferrite phase, 10 to 50% of a tempered martensite phase, and a remaining hard phase, wherein a 98% hardness is 1.5 or more times as high as a 2% hardness in a range from ? to ? of a thickness of the steel sheet, wherein a kurtosis K* of the hardness distribution between the 2% hardness and the 98% hardness is ?1.2 to ?0.4, and wherein an average crystal grain size in the steel sheet structure is 10 ?m or less.

Abstract: The steel sheet includes C: 0.04 to 0.12%, Si: 0.5 to 1.2%, Mn: 1.0 to 1.8%, P: not more than 0.03%, S: not more than 0.0030%, Al: 0.005 to 0.20%, N: not more than 0.005% and Ti: 0.03 to 0.13%, the balance being Fe and inevitable impurities, includes a microstructure containing a bainite phase at an area fraction exceeding 95% and having an average grain diameter of not more than 3 ?m, has a difference ?Hv1 of not more than 50 between a Vickers hardness value at 50 ?m from the surface and a Vickers hardness value at ¼ of a sheet thickness, has a difference ?Hv2 of not more than 40 between the Vickers hardness value at ¼ of the sheet thickness and a Vickers hardness value at ½ of the sheet thickness.

Abstract: The present invention provides a wire rod with a composition at least including: C: 0.95-1.30 mass %; Si: 0.1-1.5 mass %; Mn: 0.1-1.0 mass %; Al: 0-0.1 mass %; Ti: 0-0.1 mass %; P: 0-0.02 mass %; S: 0-0.02 mass %; N: 10-50 ppm; O: 10-40 ppm; and a balance including Fe and inevitable impurities, wherein 97% or more of an area in a cross-section perpendicular to the longitudinal direction of the wire rod is occupied by a pearlite, and 0.5% or less of an area in a central area in the cross-section and 0.5% or less of an area in a first surface layer area in the cross-section are occupied by a pro-eutectoid cementite.

Abstract: A hot-rolled steel sheet has an average value of the X-ray random intensity ratio of a {100} <011> to {223} <110> orientation group at least in a sheet thickness central portion that is in a sheet thickness range of ? to ? from a steel sheet surface of 1.0 to 6.0, an X-ray random intensity ratio of a {332} <113> crystal orientation of 1.0 to 5.0, rC which is an r value in a direction perpendicular to a rolling direction of 0.70 to 1.10, and r30 which is an r value in a direction that forms an angle of 30° with respect to the rolling direction of 0.70 to 1.10.

Abstract: A ferritic stainless steel sheet having excellent corrosion resistance and a method of manufacturing the steel sheet are provided. Specifically, the ferritic stainless steel sheet of the invention contains C of 0.03% or less, Si of 1.0% or less, Mn of 0.5% or less, P of 0.04% or less, S of 0.02% or less, Al of 0.1% or less, Cr of 20.5% to 22.5%, Cu of 0.3% to 0.8%, Ni of 1.0% or less, Ti of 4×(C %+N %) to 0.35%, Nb of less than 0.01%, N of 0.03% or less, and C+N of 0.05% or less, and has the remainder including Fe and inevitable impurities, wherein 240+35×(Cr %?20.5)+280×{Ti %?4×(C %+N %)}?280 is satisfied.

Abstract: A high strength, high toughness steel alloy is disclosed. The alloy has the following broad weight percent composition. Element Broad C 0.35-0.55 Mn 0.6-1.2 Si 0.9-2.5 P 0.01 max. S 0.001 max.? Cr 0.75-2.0? Ni 3.5-7.0 Mo + ½ W 0.4-1.3 Cu 0.5-0.6 Co 0.01 max. V + (5/9) × Nb 0.2-1.0 Fe Balance Included in the balance are the usual impurities found in commercial grades of steel alloys produced for similar use and properties. 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: 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.