Abstract: Embodiments of an ultra-fine-grained, medium carbon steel are disclosed herein. In some embodiments, the ultra-fine grained steel can have high corrosion fatigue resistance, as well as high toughness and yield strength. The ultra-fine grained steels can be advantageous for use as sucker rods in oil wells having corrosive environments.

Abstract: Disclosed in the present invention is a high-strength double-sided stainless steel clad sheet, including a substrate layer, and stainless steel clad layers clad-rolled on double sides of the substrate layer. The substrate layer consists, in mass percent, the chemical elements: C: 0.03-0.12%, 0<Si?0.30%, Mn: 0.2-1.0%, Al: 0.02-0.04%, Ti: 0.01-0.03%, Nb: 0.005-0.020%, and N: 0.003-0.006%, with the balance being iron and other inevitable impurities. Also disclosed in the present invention is a manufacturing method for the high-strength double-sided stainless steel clad sheet, including the steps of: (1) obtaining the substrate layer and the stainless steel clad layer; (2) billet making; (3) clad-rolling; and (4) solution annealing and pickling treatment: controlling the solution temperature to be 950-1020° C., and then cooling down to room temperature at an average cooling rate of 20-50° C./s.

Abstract: Provided herein is a low-alloy high-strength seamless steel pipe. The steel pipe of the present invention has a composition that contains, in mass %, C: 0.25 to 0.50%, Si: 0.01 to 0.40%, Mn: 0.3 to 1.5%, P: 0.010% or less, S: 0.001% or less, O: 0.0015% or less, Al: 0.015 to 0.080%, Cu: 0.02 to 0.09%, Cr: 0.5 to 0.8%, Mo: 0.5 to 1.3%, Nb: 0.005 to 0.05%, B: 0.0005 to 0.0040%, Ca: 0.0010 to 0.0020%, Mg: 0.001% or less, and N: 0.005% or less, and in which the balance is Fe and incidental impurities. The steel pipe has a microstructure in which the number of oxide-base nonmetallic inclusions satisfying the composition ratios represented by predefined formulae is 10 or less per 100 mm2, and in which the number of oxide-base nonmetallic inclusions satisfying the composition ratios represented by other predefined formulae is 30 or less per 100 mm2.

Abstract: The steel material according to the present disclosure contains a chemical composition consisting of, in mass %, C: 0.20 to 0.50%, Si: 0.05 to 0.50%, Mn: 0.05 to 1.00%, P: 0.030% or less, S: 0.0100% or less, Al: 0.005 to 0.100%, Cr: 0.10 to 1.50%, Mo: 0.25 to 1.50%, Ti: 0.002 to 0.050%, N: 0.0100% or less and O: 0.0100% or less, with the balance being Fe and impurities. The steel material contains an amount of dissolved C within a range of 0.010 to 0.050 mass %. The steel material also has a yield strength within a range of 655 to less than 862 MPa, and a yield ratio of the steel material is 85% or more.

Abstract: The steel material for a carburized bearing part according to the present invention contains, by mass %, C: 0.25 to 0.45%, Si: 0.15 to 0.45%, Mn: 0.40 to 1.50%, P: 0.015% or less, S: 0.005% or less, Cr: 0.60 to 2.00%, Mo: 0.10 to 0.35%, V: 0.20 to 0.40%, Al: 0.005 to 0.100%, Ca: 0.0002 to 0.0010%, N: 0.0300% or less and O: 0.0015% or less, with the balance being Fe and impurities, and satisfies Formulae (1) to (3). 1.20<0.4Cr+0.4Mo+4.5V<2.75??(1) A1/A2>0.50??(2) 2.7C+0.4Si+Mn+0.45Ni+0.8Cr+Mo+V>2.55??(3) Formula (2) shows an area fraction of sulfides containing Ca in an amount of 1 mol % or more among sulfides having an equivalent circular diameter of 1 ?m or more.

Abstract: The steel material according to the present disclosure contains a chemical composition consisting of, in mass %, C: 0.20 to 0.50%, Si: 0.05 to 1.00%, Mn: 0.05 to 1.00%, P: 0.025% or less, S: 0.0100% or less, Al: 0.005 to 0.100%, Cr: 0.20 to 1.50%, Mo: 0.25 to 1.50%, Ti: 0.002 to 0.050%, B: 0.0001 to 0.0050%, N: 0.0100% or less and O: 0.0100% or less, with the balance being Fe and impurities. The steel material contains an amount of dissolved C within a range of 0.010 to 0.050 mass %. The steel material also has a yield strength within a range of 965 to 1069 MPa, and a yield ratio of the steel material is 90% or more.

Abstract: There is provided a hot forged product having excellent wear resistance and fatigue strength even when the hot forged product is produced with a thermal refining treatment and a case hardening thermal treatment after hot forging omitted, and having a chemical composition consisting of, in mass %, C: 0.45 to 0.70%, Si: 0.01 to 0.70%, Mn: 1.0 to 1.7%, S: 0.01 to 0.1%, Cr: 0.05 to 0.25%, Al: 0.003 to 0.050%, N: 0.003 to 0.02% with the balance being Fe and impurities. The matrix at the depth of 500 ?m to 5 mm from an unmachined surface of the forged product is a ferrite-pearlite structure, in which a pro-eutectoid ferrite area fraction is 3% or less or a pearlite structure, and the average diameter of pearlite colonies in the pearlite structure at the depth of 500 ?m to 5 mm from the unmachined surface is 5.0 ?m or less.

Abstract: A spring steel wire includes, by mass %, C: 0.40% to 0.75%, Si: 1.00% to 5.00%, Mn: 0.20% to 2.00%, P: 0.0001% to 0.0500%, S: 0.0001% to 0.0500%, Cr: 0.50% to 3.50%, Al: 0.0005% to 0.0500%, N: 0.0020% to 0.0100%, Mo: 0% to 2.00%, V: 0% to 0.50%, W: 0% to 0.50%, Nb: 0% to 0.100%, Ti: 0% to 0.100%, Ca: 0% to 0.0100%, Mg: 0% to 0.0100%, Zr: 0% to 0.1000%, B: 0% to 0.0100%, Cu: 0% to 1.00%, Ni: 0% to 3.00%, and a remainder consisting of Fe and impurities. A structure includes, by area radio, tempered martensite of 90% or more. The prior austenite grain size number is No. 12.5 or higher. The presence density of iron-based carbide having an equivalent circle diameter ranging from 0.15 ?m to 0.50 ?m ranges from 0.40 pieces/?m2 to 2.00 pieces/?m2.

Abstract: A nitrided steel part excellent in bending straightening ability and bending fatigue characteristic enabling reduction of size and decrease of weight of parts or enabling demand for high load capacities to be met, using as a material a steel material containing, by mass %, C: 0.2 to 0.6%, Si: 0.05 to 1.5%, Mn: 0.2 to 2.5%, P: 0.025% or less, S: 0.003 to 0.05%, Cr: 0.05 to 0.5%, Al: 0.01 to 0.05%, and N: 0.003 to 0.025%, and having a balance of Fe and impurities, having formed on the steel surface a compound layer of a thickness 3 ?m or less comprising iron, nitrogen, and carbon and a hardened layer formed below the compound layer, and having an effective hardened layer depth of 160 to 410 ?m.

Abstract: A setting tool for setting frac plugs and the like can include a mandrel having a chamber for housing expandable gas and a gas port in fluid communication with the chamber; a firing head secured to the mandrel for igniting a power charge to generate pressurized gas within the chamber; a barrel piston housing the mandrel and connected to a sleeve for setting the frac plug; and an expansion region defined between the mandrel and the barrel piston and receiving the pressurized gas which exerts force to cause a stroke of the barrel piston over the mandrel as the expansion region expands axially. The setting tool can include various features, such as certain gas bleed systems, an enhanced shear screw assembly, a bleed port and plug assembly, a scribe line, a particular gas port configuration, a liquid escape conduit, no-shoulder barrel configuration, and/or a low-force design for frac plugs.

Abstract: A bolt is provided that has high strength and excellent hydrogen embrittlement resistance characteristics. A bolt according to an embodiment of the present invention consists of, in mass %, C: 0.32 to 0.39%, Si: 0.15% or less, Mn: 0.40 to 0.65%, P: 0.020% or less, S: 0.020% or less, Cr: 0.85 to 1.25%, Al: 0.005 to 0.060%, Ti: 0.010 to 0.050%, B: 0.0010 to 0.0030%, N: 0.0015 to 0.0080%, O: 0.0015% or less, Mo: 0 to 0.05%, V: 0 to 0.05%, Cu: 0 to 0.50%, Ni: 0 to 0.30%, and Nb: 0 to 0.05%, with the balance being Fe and impurities. The bolt satisfies Formula (1) and Formula (2), and has a tensile strength of 1000 to 1300 MPa and satisfies Formula (3). 4.9?10C+Si+2Mn+Cr+4Mo+5V?6.1??(1) Mn/Cr?0.55??(2) [dissolved Cr]/Cr?0.

Abstract: Disclosed herein is a high strength special steel including, by weight %: carbon (C): from about 0.1 to 0.5%; silicon (Si): from about 0.1 to 2.3%; manganese (Mn): from about 0.3 to 1.5%; chromium (Cr): from about 1.1 to 4.0%; molybdenum (Mo): from about 0.3 to 1.5%; nickel (Ni): from about 0.1 to 4.0%; vanadium (V): from about 0.01 to 0.50%; boron (B): from about 0.001 to 0.010%; niobium (Nb): from about 0.05 to 0.50%; and the balance of iron (Fe) and inevitable impurities.

Abstract: Disclosed herein is high-strength special steel containing about 0.1 to 0.5 wt % of carbon (C), about 0.1 to 2.3 wt % of silicon (Si), about 0.3 to 1.5 wt % of manganese (Mn), about 1.1 to 4.0 wt % of chromium (Cr), about 0.3 to 1.5 wt % of molybdenum (Mo), about 0.1 to 4.0 wt % of nickel (Ni), about 0.01 to 0.50 wt % of vanadium (V), about 0.05 to 0.50 wt % of titanium (Ti), and the remainder of iron (Fe) and other inevitable impurities.

Abstract: A non-heat treated steel according to the present invention includes, as steel composition, by mass %, 0.20 to 0.60% of C, 0.50 to 2.0% of Si, 0.20 to 2.0% of Mn, 0.010 to 0.15% of P, 0.010 to 0.15% of S, 0.10 to 0.50% of V. 0.002 to 0.02% of N, and a balance consisting of Fe and impurities, in which, when a ratio of a maximum value of a V content in the steel to an average value of the V content in the steel in a cross section of the steel is defined as a segregation ratio of V, the segregation ratio of V is 1.0 or more and less than 3.0.

Abstract: A steel alloy comprising from: (a) 0.6 to 0.9 wt. % carbon, (b) 0.1 to 0.5 wt. % silicon, (c) 0.1 to 1.5 wt. % manganese, (d) 1.5 to 2.0 wt. % chromium, (e) 0.2 to 0.6 wt. % molybdenum, and up to: (f) 0.25 wt. % nickel, (g) 0.3 wt. % copper, (h) 0.2 wt. % vanadium, (i) 0.2 wt. % cobalt, (j) 0.2 wt. % aluminum, (k) 0.1 wt. % niobium, (l) 0.2 wt. % tantalum, (m) 0.05 wt. % phosphorous, (n) 0.03 wt. % sulphur, (o) 0.075 wt. % tin, (p) 0.075 wt. % antimony, (q) 0.075 wt. % arsenic, (r) 0.01 wt. % lead, (s) 350 ppm nitrogen, (t) 100 ppm oxygen, (u) 50 ppm calcium, (v) 50 ppm boron, (w) 50 ppm titanium, the balance iron, including any other unavoidable impurities, wherein the alloy comprises molybdenum and silicon in a weight ratio of 0.4?Mo/Si?6.0 and comprises molybdenum and chromium in a weight ratio of 0.1?Mo/Cr?0.4.

Abstract: A hot-dip galvanized steel sheet contains specific amounts of C, Si, Mn, P, S, Ti, Al, and N with the remainder being iron and unavoidable impurities. Bainitic ferrite, martensite, retained ?, and ferrite (?) are present each in a specific area ratio. The remainder ? has a specific C concentration. Sub-grains in the recrystallized ? and un-recrystallized ? have a specific grain diameter. The surface area ratio of ? and worked ? having a grain diameter of 5 ?m or more is 5% or less. The average particle diameter of TiC particles inside ? grains is 10 nm or less.

Abstract: There is a gear set. The gear set has a) a first gear having a first surface and b) an intermeshing second gear having a second surface. The first and second surfaces each, independently, have an isotropic arithmetic mean roughness, Ra, of about 0.0762 micrometers/3 microinches or less and are lubricated. There is also a method for increasing the contact surface-fatigue life of a gear set.

Abstract: Disclosed is a steel having high manufacturability and better rolling-contact fatigue properties. The steel contains C of 0.65% to 1.30%, Si of 0.05% to 1.00%, Mn of 0.1% to 2.00%, P of greater than 0% to 0.050%, S of greater than 0% to 0.050%, Cr of 0.15% to 2.00%, Al of 0.010% to 0.100%, N of greater than 0% to 0.025%, Ti of greater than 0% to 0.015%, and O of greater than 0% to 0.0025% and further contains iron and unavoidable impurities. Al-containing nitrogen compound particles dispersed in the steel have an average equivalent circle diameter of 25 to 200 nm, and Al-containing nitrogen compound particles each having an equivalent circle diameter of 25 to 200 nm are present in a number density of 1.1 to 6.0 per square micrometer.

Abstract: There is provided a steel for induction hardening in which cracks are less liable to occur and high hardness and seizure resistance are attained even if a tempering process after induction hardening is omitted. The steel for induction hardening according to the present invention contains, by mass percent, C: 0.20 to 0.34%, Si: at most 0.20%, Mn: 0.75 to 2.0%, P: at most 0.03%, S: at most 0.20%, Cr: 0.05 to 1.2%, Ti: at least 0.002% and less than 0.030%, Al: 0.005 to 0.04%, and N: 0.0040 to 0.020%, the balance being Fe and impurities, and satisfies Formula (1): 1.20?Mn+Cr?2.10??(1) where the content (mass %) of each element is substituted for each of the symbols of elements in Formula (1).

Abstract: The high-strength thick steel plate for storage container contains: C: 0.12-0.16% (means mass %, hereinafter the same), Si: 0.05-0.5%, Mn: 1-1.5%, Al: 0.01-0.05%, Nb: 0.003-0.02%, Mo: 0.03-0.3%, V: 0.025-0.04%, Cr: 0.05-0.3%, Cu: 0.05-0.5%, Ni: 0.15-0.55%, Ca: 0.0005-0.006% respectively, and the RP value as defined by an equation (1) below satisfies the relation of RP?4.5×10?8. RP={[Nb]/93+1/60×[V]/51}×[Mo]/96??(1) where [Nb], [V] and [Mo] respectively represent the content (mass %) of Nb, V and Mo.

Abstract: An object of the present invention is to provide an Ni-containing steel plate which is low in cost and has excellent low-temperature toughness. In view of the object, the Ni-containing steel plate of the present invention has a chemical composition containing by mass % C: 0.01% to 0.15%, Si: 0.02% to 0.20%, Mn: 0.45% to 2.00%, P: 0.020% or less, 5: 0.005% or less, Al: 0.005% to 0.100% Ni: 5.0 to 8.0%, and the balance being Fe and incidental impurities, and has a microstructure containing less than 1.7% by volume fraction of retained austenite when cooled to liquid nitrogen temperature, and having an average grain size of crystal grains surrounded by high-angle grain boundaries with an orientation difference of 15° or more of 5 ?m or less by equivalent circle diameter.

Abstract: A bearing steel material which contains 0.8-1.1 mass % C, 0.15-0.8 mass % Si, 0.1-1.0 mass % Mn, 1.3-1.8 mass % Cr, up to 0.05 mass % P (0 mass % is excluded), up to 0.015 mass % S (0 mass % excluded), 0.0002-0.005 mass % Al, 0.0002-0.0020 mass % Ca, 0.0005-0.010 mass % Ti, up to 0.0080 mass % N (0 mass % is excluded), and up to 0.0025 mass % O (0 mass % is excluded). The steel material contains oxide inclusions which have an average composition that comprises, in terms of mass %, 20-50% CaO, 20-50% Al2O3, 20-70% SiO2, and 3-10% TiO2.

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: Identifying a stable phase of a binary alloy comprising a solute element and a solvent element. In one example, at least two thermodynamic parameters associated with grain growth and phase separation of the binary alloy are determined, and the stable phase of the binary alloy is identified based on the first thermodynamic parameter and the second thermodynamic parameter, wherein the stable phase is one of a stable nanocrystalline phase, a metastable nanocrystalline phase, and a non-nanocrystalline phase.

Abstract: A steel for heat treatment, which exhibits high strength and high toughness even when the heat treatment (such as quenching and tempering) of the steel is conducted under conventional conditions in an after stage. The steel for heat treatment contains C: 0.10 to 0.70 mass %, Mn: 0.1 to 3.0 mass %, Al: 0.005 to 2.0 mass %, P: 0.050 mass % or less, S: 0.50 mass % or less, O: 0.0030 mass or less, N: 0.0200 mass % or less, and one or more selected from the group consisting of Ti: 0.30 mass % or less and Nb: 0.30 mass or less with the balance being Fe and unavoidable impurities, and has a TH value of 1.0 or above as calculated according to the formula: ({Ti}/48+{Nb}/93) 104 and grain diameters of 10 ?m or below. {Ti} and {Nb} refer respectively to the contents of Ti and Nb in precipitates of 5 to 100 nm in size as determined about their respective extraction residues.

Abstract: A stainless steel alloy adapted for a golf club head includes 0.03 wt % of carbon, 0.01 wt % of phosphorus, 0.1 wt % of silicon, 0.05 wt % of calcium, 0.03 wt % of zirconium, 0.1 wt % of manganese, 0.01 wt % of sulfur, 4 wt % to 5.1 wt % of molybdenum, 18 wt % to 19 wt % of nickel, 7 wt % to 12 wt % of cobalt, 0.05 wt % to 0.15 wt % of aluminum, 0.1 wt % to 0.8 wt % of titanium, and a balance of iron based on 100 wt % of the stainless steel alloy, wherein the content of iron is more than 0 wt %.

Abstract: A steel sheet for hot pressing use according to the present invention has a specified chemical component composition, wherein some of Ti-containing precipitates contained in the steel sheet, each of which having an equivalent circle diameter of 30 nm or less, have an average equivalent circle diameter of 6 nm or less, the precipitated Ti amount and the total Ti amount in the steel fulfill the relationship represented by formula (1) shown below, and the sum total of the fraction of bainite and the fraction of martensite in the metal microstructure is 80 area % or more. Precipitated Ti amount (mass %)?3.4[N]?0.5×[(total Ti amount (mass %))?3.4[N]]??(1) (In the formula (1), [N] represents the content (mass %) of N in the steel.

Abstract: A method forms a steel sheet having a tensile strength of 440 MPa or more into a press-formed part including a flange portion and other portions by press forming. The method includes: heating the steel sheet to a temperature of 400° C. to 700° C.; and press-forming the heated steel sheet by crash forming to obtain a press-formed part such that an average temperature difference among a flange portion and other portions of the press-formed part immediately after the formation is kept within 100° C. Geometric changes such as springback that occur in a panel can thus be suppressed, dimensional accuracy of the panel can be enhanced accordingly, and the desired mechanical properties can easily be obtained in the press-formed part.

Abstract: The steel for hot forming has the following composition in weight %: C: 0.10-0.25, Mn: 1.4-2.8, Si: ?1.0, Cr: ?1.0, Ti: ?0.05, Nb: ?0.05, V: ?0.1, Mo: ?0.1, Al: ?0.05, P: ?0.02, S: ?0.005, Ca: ?0.005, O: ?0.01, N: ?0.02, B: ?0.0004, the remainder being iron and unavoidable impurities. Also disclosed is a strip, sheet or blank produced with such a steel, a method for producing a hot formed product, such a product and the use thereof.

Abstract: A method of forming a steel sheet having a tensile strength of 440 MPa or more into a press-formed part including a flange portion and other portions by press forming includes: heating the steel sheet to a temperature of 400° C. to 700° C.; and press-forming the heated steel sheet using draw forming to obtain a press-formed part, with the steel sheet being held at a press bottom dead point in the die for one second to five seconds. Geometric changes such as springback that occur in a panel can thus be suppressed, the dimensional accuracy of the panel can be enhanced, and the desired mechanical properties can easily be obtained in the press-formed part.

Abstract: A steel comprises, by mass percent, C: 0.10 to 0.15%, Si: not less than 0.02% and less than 0.10%, Mn: more than 0.90% and not more than 2.50%, P?0.030%, S?0.050%, Cr: 0.80 to 2.0%, V: 0.05 to 0.50%, Al: 0.01 to 0.07%, N?0.0080%, O?0.0030%, and one or more selected from Mo, Cu, Ni, Ti, Nb, Zr, Pb, Ca, Bi, Te, Se and Sb, the balance being Fe and impurities. The composition satisfies [35?Mn/S?200], [20?(669.3×logeC?1959.6×logeN?6983.3)×(0.067×Mo+0.147×V)?80], [140×Cr+125×Al+235×V?160] and [150?511×C+33×Mn+56×Cu+15×Ni+36×Cr+5×Mo+134×V?200].

Abstract: Provided is a maraging steel excellent in fatigue characteristics, including, in terms of % by mass: C: ?0.015%, Ni: from 12.0 to 20.0%, Mo: from 3.0 to 6.0%, Co: from 5.0 to 13.0%, Al: from 0.01 to 0.3%, Ti: from 0.2 to 2.0%, O: ?0.0020%, N: ?0.0020%, and Zr: from 0.001 to 0.02%, with the balance being Fe and unavoidable impurities.

Abstract: A steel wire rod or steel bar as hot-rolled, including: by mass %: C: 0.1 to 0.6%, Si: 0.01 to 1.5%, Mn: 0.05 to 2.5%, Al: 0.015 to 0.3%, and N: 0.0040 to 0.0150%, and P: limited to 0.035% or less and S: limited to 0.025% or less, and the balance substantially consisting of iron and unavoidable impurities, wherein a depth of d (mm) from the surface of the surface layer region with 20 HV 0.2 or more higher, relative to HV 0.2 that is the average hardness in the region where the depth from the surface is from sectional radius R×0.5 (mm) to the center satisfies the formula (1); the steel structure of the surface layer region has a ferrite fraction of 10% or less by area ratio, with the balance being one or two or more of martensite, bainite and pearlite; the steel structure where the depth from the surface is from the sectional radius R×0.

Abstract: A steel material for nitriding has a composition comprising, by mass percent, C: more than 0.15% and not more than 0.35%, Si?0.20%, Mn: 0.10 to 2.0%, P?0.030%, S?0.050%, Cr: 0.80 to 2.0%, V: 0.10 to 0.50%, Al: 0.01 to 0.06%, N?0.0080%, O?0.0030%, and optionally one or more elements of Mo, Cu, Ni, Ti, Nb, Zr, Pb, Ca, Bi, Te, Se and Sb, the balance being Fe and impurities. The composition satisfies the conditions of [20?(669.3×logeC?1959.6×logeN?6983.3)×(0.067×Mo+0.147×V)?80] and [140×Cr+125×Al+235×V?160]. The microstructure is a ferritic-pearlitic structure, a ferritic-bainitic structure, or a ferritic-pearlitic-bainitic structure. The area fraction of ferrite is 20% or more and the precipitate content of V is 0.10% or less.

Abstract: A base metal for high-toughness clad plate having excellent toughness at a welded joint contains, in terms of mass %, C: 0.030 to 0.10%, Si: 0.10 to 0.30%, Mn: 1.00 to 1.60%, P: 0.015% or less, S: 0.003% or less, V: less than 0.010%, and at least one selected from Mo: 0.05 to 0.50%, Nb: 0.010 to 0.060%, Ti: 0.005 to 0.020%, Al: 0.040% or less, Ca: 0.0010 to 0.0040%, and N: 0.0030 to 0.0060%, the balance being Fe and unavoidable impurities, in which a percent ductile fracture is 85% or more in a ?20° C. DWTT test and vE?20° C. is 100 J or more at a HAZ 3 mm position.

Abstract: A steel strip for coiled tubing contains, in terms of percent by mass, C: 0.10% or more and 0.16% or less, Si: 0.1% or more and 0.5% or less, Mn: 0.5% or more and 1.5% or less, P: 0.02% or less, S: 0.005% or less, Sol. Al: 0.01% or more and 0.07% or less, Cr: 0.4% or more and 0.8% or less, Cu: 0.1% or more and 0.5% or less, Ni: 0.1% or more and 0.3% or less, Mo: 0.1% or more and 0.2% or less, Nb: 0.01% or more and 0.04% or less, Ti: 0.005% or more and 0.03% or less, N: 0.005% or less, and the balance of Fe and inevitable impurities.

Abstract: A low alloy steel, containing, by mass percent, C: 0.01 to 0.15%, Si: 3% or less, Mn: 3% or less, B: 0.005 to 0.050%, and Al: 0.08% or less, and the balance being Fe and impurities, wherein in the impurities, N: 0.01% or less, P: 0.05% or less, S: 0.03% or less, and O: 0.03% or less. In the alloy steel, a HAZ has excellent resistance to embrittlement attributable to hydrogen such as stress corrosion cracking in wet hydrogen sulfide environments.

Abstract: A steel for welding includes steel components in which PCTOD is less than or equal to 0.065%, CeqH is less than or equal to 0.225%, FB is greater than or equal to 0.0003%, and Bp is 0.09% to 0.30%. In the steel for welding, in a thickness center portion of a cross-section in a thickness direction, the number of oxide particles having an equivalent circle diameter of 2 ?m or greater is less than or equal to 20 particles/mm2 and the number of Ti oxides having an equivalent circle diameter of 0.05 ?m to 0.5 ?m is 1.0×103 particles/mm2 to 1.0×105 particles/mm2.

Abstract: Provided is a hot-rolled steel sheet having a composition containing 0.04 mass percent to 0.20 mass percent C, 0.7 mass percent to 2.3 mass percent Si, 0.8 mass percent to 2.8 mass percent Mn, 0.1 mass percent or less P, 0.01 mass percent or less S, 0.1 mass percent or less Al, and 0.008 mass percent or less N, the remainder being Fe and inevitable impurities. Internal oxides containing one or more selected from the group consisting of Si, Mn, and Fe are present at grain boundaries and in grains in a base metal. The internal oxides present at the grain boundaries in the base metal are located within 5 ?m from the surface of the base metal. The difference between the depths at which the internal oxides are formed in the cross direction of the steel sheet is 2 ?m or less.

Abstract: This H-beam steel contains, in mass %, C, Si, Mn, Al, Ti, N, O, Nb, and B. The H-beam steel has composition in which the amount of Nb and the amount of B satisfy, in mass %, 0.070?Nb+125B?0.155, and has a metal structure in which, in a microstructure, an area fraction of bainite is not less than 70%, a total of an area fraction of pearlite and an area fraction of cementite is not more than 15%, and the remainder is at least one of ferrite and island martensite. The effective crystalline-grain size of the bainite is not more than 40 ?m, and the thickness of a flange falls in a range of 12 to 40 mm.

Abstract: The present invention provides spring use heat treated steel which is cold coiled, can achieve both sufficient atmospheric strength and coilability, has a tensile strength of 2000 MPa or more, and can improve the performance as a spring by heat treatment after spring fabrication, that is, high strength spring-use heat treated steel characterized by containing, by mass %, C: 0.45 to 0.9%, Si: 1.7 to 3.0%, and Mn: 0.1 to 2.0%, restricting N: to 0.007% or less, having a balance of Fe and unavoidable impurities, and satisfying, in terms of the analyzed value of the extracted residue after heat treatment, [amount of Fe in residue on 0.2 ?m filter/[steel electrolysis amount]×100?1.1.

Abstract: This high-strength steel plate has a component composition including, by mass %, C: 0.02-0.3%, Si: 1-3%, Mn: 1.8-3%, P: 0.1% or less, S: 0.01% or less, Al: 0.001-0.1%, N: 0.002-0.03%, the rest consisting of iron and impurities. Said steel plate has a microstructure including, in terms of area ratio relative to the entire microstructure, each of the following phases: bainitic ferrite: 50-85%; retained ?; 3% or greater; martensite+the aforementioned retained ?; 10-45%; and ferrite: 5-40%. The C concentration (C?R) in the aforementioned retained austenite is 0.3-1.2 mass %, part or all of the N in the aforementioned component composition is solid solution N, and the amount of said solid solution N is 30-100 ppm.

Abstract: A high-strength cold-rolled steel sheet excellent in ductility, work hardenability, and stretch flangeability, and having tensile strength of 780 MPa or more includes: a chemical composition containing, in mass percent, C: more than 0.020% to less than 0.30%, Si: more than 0.10% to 3.00% or less, Mn: more than 1.00% to 3.50% or less; and metallurgical structure whose main phase is a low-temperature transformation product, and whose secondary phase contains retained austenite. The retained austenite has a volume fraction relative to overall structure of more than 4.0% to less than 25.0% and an average grain size of less than 0.80 ?m, and of the retained austenite, the number density of retained austenite grains whose grain size is 1.2 ?m or more is 3.0×10?2 grains/?m2 or less.

Abstract: The present invention provides high strength steel pipe for line pipe superior in low temperature toughness suppressed in drop of toughness of the HAZ and a method of production of the same, more particularly high strength steel plate for line pipe used as a material for high strength steel pipe for line pipe and a method of production of the same, in particular high strength steel pipe for line pipe superior in low temperature toughness characterized in that the chemical compositions of the base metal is, by mass %, C: 0.020 to 0.080%, Si: 0.01 to 0.50%, Mo: 0.01 to 0.15%, Al: 0.0005 to 0.030%, and Nb: 0.0001 to 0.030% contained in a range of C+0.25Si+0.1Mo+Al+Nb: 0.100% or less and the mixture of austenite and martensite present along prior austenite grain boundaries of the reheated part of the heat affected zone has a width of 10 ?m or less and a length of 50 ?m or less.

Abstract: A steel plate for line pipes containing, in terms of % by weight, C: 0.02 to 0.06%, Si: 0.5% or less, Mn: 0.8 to 1.6%, P: 0.008% or less, S: 0.0008% or less, Al: 0.08% or less, Nb: 0.005 to 0.035%, Ti: 0.005 to 0.025%, and Ca: 0.0005 to 0.0035%, and optionally contains one or more of Cu: 0.5% or less, Ni: 1% or less, Cr: 0.5% or less, Mo: 0.5% or less and V: 0.1% or less, and has a CP value of 0.95 or less represented by CP=4.46C(%)+2.37Mn(%)/6+{1.18Cr(%)+1.95Mo(%)+1.74V(%)}/5+{1.74Cu(%)+1.7Ni(%)}/15+22.36P(%), and a Ceq value of 0.30 or more represented by Ceq=C(%)+Mn(%)/6+{Cr(%)+Mo(%)+V(%)}/5 +{Cu(%)+Ni(%)}/15.

Abstract: The invention provides a hot-forging micro-alloyed steel and a hot-rolled steel which achieve excellent fracture-splitability and machinability, without impairing productivity or mechanical properties and without addition of Pb or the like. It also provides a component made of hot-forged micro-alloyed steel. The hot-forging micro-alloyed steel comprises, in mass %, C: greater than 0.35 to 0.60%, Si: 0.50 to 2.50%, Mn: 0.20 to 2.00%, P: 0.010 to 0.150%, S: 0.040 to 0.150%, V: 0.10 to 0.50%, Zr: 0.0005 to 0.0050%, Ca: 0.0005 to 0.0050% and N: 0.0020 to 0.0200%, Al being limited to less than 0.010%, and a balance substantially of Fe and unavoidable impurities.

Abstract: To provide an oil-well steel pipe having excellent SSC resistance. The oil-well steel pipe according to the present invention contains, by mass percent, C: 0.15 to 0.35%, Si: 0.1 to 0.75%, Mn: 0.1 to 1.0%, Cr: 0.1 to 1.7%, Mo: 0.1 to 1.2%, Ti: 0.01 to 0.05%, Nb: 0.010 to 0.030%, Al: 0.01 to 0.1%, P: at most 0.03%, S: at most 0.01%, N: at most 0.007%, and O: at most 0.01%, the balance being Fe and impurities. The Ti content and the Nb content in a residue obtained by bromine-methanol extraction satisfy equation (1): 100×[Nb]/([Ti]+[Nb])?27.5??(1) where the Ti content (mass %) and the Nb content (mass %) in the residue are substituted for [Ti] and [Nb].

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 spring steel, which is finally formed into a spring, by making use of, at a maximum, the temper softening resistance effect due to alloying elements while suppressing the formation of hard inclusions of SiO2 and the generation of decarburization, which may cause deterioration of fatigue characteristics of the spring. The spring steel is characterized by comprising, in % by mass, C: 0.50 to 0.70%, Si: 1.00 to 5.00%, Mn: 0.30 to 2.00%, P: 0.0002 to 0.0500%, S: 0.0002 to 0.0500%, Cr: 0.10 to 3.50%, Al: 0.0005 to 0.0500%, and N: 0.0020 to 0.0100%, with the balance being Fe and inevitable impurities, wherein the H-value defined by the following equation (a) is 160 or more, and the C-value defined by the following equation (b) is 3.25 or less: H=33.6[C]+10.0[Si]+5.95[Mn]+11.1[Cr]+90.0??(a), and C=[Si]/[Mn]??(b).

Abstract: There is provided an induction hardening steel excellent in quenching crack resistance. The induction hardening steel of the present embodiment includes, by mass percent, C: 0.35 to 0.6%, Si: at least 0.01% and less than 0.40%, Mn: 1.0 to 2.0%, S: more than 0.010% and at most 0.05%, Cr: 0.01 to 0.5%, Al: 0.001 to 0.05%, N: Ti/3.4 to 0.02%, and Ti: 0.005 to 0.05%, the balance being Fe and impurities, and satisfies the following formula (1): 2S-3Ti<0.040??(1) where, into each element symbol in formula (1), the content (mass %) of the corresponding element is substituted.