Abstract: Materials, methods and techniques relate to steel alloys. In some instances, steel alloys can include chromium, molybdenum, vanadium, copper, nickel, manganese, niobium, aluminum, and iron. In some instances, exemplary steel alloys are subjected to solution carburizing, tempering, and/or plasma nitriding. Exemplary steel alloys are typically precipitation strengthened carburizable and nitridable steel alloys.

Abstract: A carburized steel component, comprising a steel base including, by weight percent, from 0.08% to 0.35% carbon, 0.5% to 1.3% manganese, 0% to 0.35% silicon, 0.2% to 2.0% chromium, 0% to 4% nickel, 0% to 0.50% molybdenum, 0% to 0.06% niobium, and a remaining weight percent of iron, and a carburized layer of above 0.35% by weight carbon from a surface of the carburized layer to a carburized layer depth, wherein the carburized layer depth is from 0.5 mm to 3.0 mm, wherein the carburized layer comprises a microstructure including martensite, retained austenite, carbide, and less than 2% by volume non-martensitic transformation products (NMTP), and wherein the carburized layer includes a prior austenite average grain size of 3.0-8.0 microns from the surface to a depth of at least 0.2 mm.

Abstract: An inner ring or and outer ring for a roller bearing includes: 0.30-0.45 wt. % carbon, 0.1-0.7 wt. % silicon, 0.6-0.9 wt. % manganese, 0.9-1.2 wt. % chromium, 0.15-0.7 wt. % molybdenum, 0-2.0 wt. % nickel, 0-0.02 wt. % phosphorus, and 0-0.02 wt. % sulfur, the balance being iron and unavoidable impurities. The microstructure of the steel composition contains bainite, and a carbonitrided case layer is provided on a surface of the inner ring or outer ring.

Abstract: An example bushing has three portions along its radial direction including an inner portion most proximal to a central hole of the bushing, an outer portion most distal from the center hole, and a core portion between the inner portion and the outer portion. The core portion has a hardness that is less than the hardness of the inner portion or the outer portion of the bushing. The bushing may be formed using high carbon steel, which in some cases may be spheroidal cementite crystal structure. A rough bushing may be formed using the high carbon steel, followed by a direct hardening process, and an induction hardening process on the inner surface most proximal to the central hole of the bushing. The induction hardening on the inner surface may harden the outer portion while tempering the core portion of the bushing.

Abstract: The invention relates to a stainless steel. The stainless steel consists of in weight % (wt. %): C 0.32-0.50 Si 0.1-1.0 Mn 0.1-0.8 Cr11-14 Mo 1.8-2.6 V 0.35-0.70 N 0.05-0.19 optional elements, balance Fe and impurities.

Abstract: A case hardening steel includes a chemical composition containing C: 0.10 mass % to 0.35 mass %, Si: 0.01 mass % to 0.13 mass %, Mn: 0.30 mass % to 0.80 mass %, P: 0.02 mass % or less, S: 0.03 mass % or less, Al: 0.01 mass % to 0.045 mass %, Cr: 0.5 mass % to 3.0 mass %, B: 0.0005 mass % to 0.0040 mass %, Nb: 0.003 mass % to 0.080 mass %, N: 0.0080 mass % or less, Ti as an impurity: 0.005 mass % or less, and the balance being Fe and incidental impurities, and satisfying Formulae (1) and (2): 3.0[% Si]+9.2[% Cr]+10.3[% Mn]?10.0??(1) 3.0[% Si]+1.0[% Mn]<1.0??(2) where [% M] represents the content of element M (mass %).

Abstract: A machine component includes a core made up of a steel for machine structural use, and a medium carbon-containing layer and a high carbon-containing layer formed of the steel for machine structural use, the medium carbon-containing layer covering the core, the high carbon-containing layer covering the medium carbon-containing layer and having a carbon concentration of 0.8-1.5%. The high carbon-containing layer is made up of a martensitic structure having carbides dispersed therein and a residual austenitic structure, wherein spheroidized carbides with an aspect ratio of 1.5 or less constitute 90% or more of a total number of the carbides, and the number of spheroidized carbides on prior austenite grain boundaries is 40% or less of the total number of the carbides.

Abstract: Steel materials for continuously variable transmissions sheaves, and methods for manufacturing a continuously variable transmission sheaves, are provided. In the disclosed steel materials for continuously variable transmission sheaves, the steel materials satisfy the following expressions: 13.9?Fn1?15.5, and 1.20?Fn2?4.35 (in which Fn1=7×Cr?6×Si+4×Mn; and Fn2=Al×N×104).

Abstract: A rolling bearing is disclosed which comprises an outer ring and an inner ring, wherein rolling elements are arranged between the outer ring and the inner ring, and wherein the rolling elements are spaced apart by a cage being arranged between the outer ring and the inner ring, wherein the cage is made of polymer containing reinforcing fibers, and the outer ring and/or the inner ring are steel rings with fine carbide precipitation.

Abstract: A variator for a mechanical transmission system is disclosed. Transfer means are in rolling contact with input and output members of the variator to transfer rotary motion between them. The input member is coupled to the variator input through a first biasing device arranged to exert a first biasing force on the variator according to a first, input gain which relates input torque acting on the input member and the first biasing force. The output member is coupled to the variator output through a second biasing device arranged to exert a second biasing force on the variator according to a second, output gain which relates output torque acting on the output member and the second biasing force. The first and second biasing forces clamp the variator to provide traction. The first, input gain and second, output gain are different, which, at least in specific variator applications, optimises the traction coefficient.

Abstract: The present invention provides a carburized part which is formed by processing a steel into a shape of a part and performing a carburizing treatment on the steel, the steel having a composition consisting essentially of, in terms of % by mass: 0.10% to 0.40% of C; 0.05% to 2.00% of Si; 0.30% to 2.00% of Mn; 0.30% to 3.00% of Cr; 0.025% or less of N; and as a pinning particle forming element which forms a pinning particle by nitrification, one or two or more elements selected from: 0.020% to 0.100% of Al; 0.01% to 0.20% of Nb; and 0.005% to 0.20% of Ti, and optionally: 0.80% or less of Mo, with the remainder being Fe and inevitable impurities, in which a crystal grain size number of a surface layer of the part at a depth of 50 ?m or less from a surface is greater than 5, and the crystal grain size number of an inner portion of the part at a depth of 3 mm or more from the surface is 5 or less.

Abstract: A front cover assembly is disclosed. The front cover assembly includes a front cover body having a disc shape and a hub having a tubular shape. The front cover body includes a tubular portion in a center part thereof. The tubular portion is closed at one end thereof. The hub includes an engaging portion integrated with at least part of an outer peripheral surface thereof. The hub includes a coupling portion configured to extract power on an inner peripheral surface thereof. The engaging portion is press-fitted to the tubular portion of the front cover body.

Abstract: A profiled element suitable for repeated deformation and relaxation, which profiled element is made from a case hardened stainless steel including at least 9% chromium and up to 6% nickel which profiled element has a material thickness in the range of from 0.2 mm to 3 mm and a nitrogen martensitic case with a case depth in the range of from 10 ?m to 50 ?m and a surface hardness of up to 750 HV0.05 and to a method of case hardening a workpiece made from a stainless steel including at least 9% chromium and up to 5% nickel, which workplace has a material thickness in the range of from 0.2 mm to 3 mm. The profiled element may be a fixing element for fixing a bearing element and a fastening element against each other, and the method is suited in the manufacture of the fixing element.

Abstract: A high strength, high toughness steel alloy is disclosed. The alloy has the following weight percent composition. Element C 0.30-0.55 Mn ?0.6-1.75 Si 0.9-2.8 Cr 0.6-2.5 Ni 2.70-7.0? Mo + ½ W 0.25-1.3? Cu 0.30-1.25 Co ?0.01 max. V + ( 5/9) × Nb 0.10-1.0? Ti ?0.01 max. Al 0.015 max. Ca 0.005 max. The alloy further includes a grain refining element selected from the group consisting of 0.0001-0.01% Mg, 0.001-0.025% Y, and a combination thereof. The balance of the alloy is iron and the usual impurities found in commercial grades of steel alloys produced for similar use and properties. In this regard phosphorus is limited to not more than about 0.01% and sulfur is limited to not more than about 0.001%. 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 weight percent composition set forth above.

Abstract: A method of manufacturing a high-strength steel sheet includes, on a mass percent basis, 0.03%-0.10% C, 0.01%-0.5% Si, 0.001%-0.100% P, 0.001%-0.020% S, 0.01%-0.10% Al, 0.005%-0.012% N, the balance being Fe and incidental impurities, and microstructures that do not contain a pearlite microstructure, wherein, when Mnf=Mn [% by mass]?1.71×S [% by mass], Mnf is 0.3 to 0.6, including: forming a slab by vertical-bending type continuous casting or bow type continuous casting, wherein surface temperature of a slab corner in a region where the slab undergoes bending deformation or unbending deformation is 800° C. or lower, or 900° C. or higher; forming a steel sheet by hot-rolling the slab followed by cold rolling; annealing the steel sheet after the cold rolling; and skinpass rolling at a draft of 3% or less after the annealing.

Abstract: A method of manufacturing a machine component includes the steps of: preparing a member made of steel; forming a film containing vanadium at a surface by subjecting the member to oxidation; and forming a nitrogen-enriched layer by heating the member having the film formed in a heat treatment gas atmosphere containing nitrogen gas and absent of ammonia gas for carbonitriding.

Abstract: Disclosed is a cold formable spring steel wire excellent in cold cutting capability and fatigue properties, in which the steel wire satisfies given composition, has an average globular carbide particle size [?(ab)]:1.0 ?m or less with aspect ratio (a/b, a: major axis of carbide, b: minor axis of carbide) being 2 or less, a ratio (area %) of the globular carbide in the steel: (0.1 to 3)×amount (mass %) of C in the steel, an amount (mass %) of Cr in the globular carbide: [0.4×amount (mass %) of Cr in the steel] or less, hardenability factor (Dic): between 110 mm and 450 mm, and tensile stress of 2000 MPa or more.

Abstract: A bearing component formed from a steel composition and providing carbon, silicon, manganese, chromium, cobalt, vanadium, and at least one of the following elements sulphur, phosphorous, molybdenum, aluminum, arsenic, tin, antimony, and the balance iron, together with impurities.

Abstract: Provided is a steel for machine structural use which has excellent machinability (particularly, with respect to tool life) for both intermittent cutting with a high-speed steel tool and continuous cutting with a cemented carbide tool while maintaining strength properties required of the steel for machine structural use. Specifically, the steel for machine structural use contains C: 0.05-0.9 mass %, Si: 0.03-2 mass %, Mn: 0.2-1.8 mass %, P: 0.03 mass % or less, S: 0.03 mass % or less, Al: 0.1-0.5 mass %, N: 0.002-0.017 mass %, and O: 0.003 mass % or less, and contains one or more selected from a group consisting of Ti: 0.05 mass % or less (excluding 0 mass %) and B: 0.008 mass % or less (excluding 0 mass %), with the remainder being iron and unavoidable impurities, and satisfies all of the following inequalities (1)-(3) below: (1): [N]?0.3[Ti]?1.4[B]<(0.0004/[Al])?0.002; (2): [Ti]?[N]/0.3<0.005; and (3): [B]?([N]?0.3[Ti])/1.4<0.003 when [Ti]?[N]/0.3<0 and [B]<0.003 when [Ti]?[N]/0.3?0.

Abstract: A manufacturing method for a composite steel part including manufacturing a first steel part by preparing an intermediate product in which an extra portion is added, and heating the intermediate product to an austenitizing temperature in a carburizing atmosphere to form a carburized layer, cooling the intermediate product at a rate less than a cooling rate at which martensitic transformation is caused and in which the intermediate product is cooled to a temperature equal to or less than a temperature at which structure transformation due to the cooling is completed, heating the intermediate product to an austenitizing range by high-density energy and thereafter cooled at a rate equal to or more than the cooling rate at which martensitic transformation is caused to form a carburized quenched portion, cutting the extra portion of the intermediate product, and welding the first steel part and the second steel part to each other.

Abstract: A manufacturing method for a composite steel part including preparing an intermediate product in which an extra portion, which has a thickness equal to or more than that of a carburized layer to be formed in a subsequent carburizing step, has been added to a welding expected portion, carburizing the intermediate product by heating to an austenitizing temperature or more in a carburizing atmosphere, then cooling the intermediate product at a cooling rate less than a rate at which martensitic transformation occurs and without completing structural transformation due to the cooling, quenching a portion of the intermediate product after heating to an austenitizing range by high-density energy and thereafter cooling to cause martensitic transformation to form a carburized quenched portion, removing an extra portion of the intermediate product; and then welding a second steel part to the welding expected portion.

Abstract: This case hardened steel has a composition including, in mass %: C: 0.05 to 0.45%; Si: 0.01 to 1.0%; Mn: over 0 to 2.0%; Al: 0.001 to 0.06%, N: 0.002 to 0.03%, S: over 0 to 0.1%, P: over 0 to 0.05%; and balance: Fe and inevitable impurities. Equation (1) described below and Equation (2) described below are satisfied in equiaxed zone, or Equation (3) described below is satisfied in columnar zone. Re=(Ae/Ao)×100?30%??Equation (1) (Cmin,1/Co)?0.95??Equation (2) (Cmin,2/Co)?0.

Abstract: Disclosed are a method for adjusting the pore size of a porous metal material and the pore structure of a porous metal material. The method comprises: permeating at least one element into the surface of the pores of the material to generate a permeated layer on the surface of the pores, so that the average pore size of the porous material is reduced to within a certain range, thus obtaining a pore structure of the porous metal material having the pores distributed on the surface of the material and the permeated layer provided on the surface of the pores.

Abstract: The present invention relates to a mechanical part, which is obtained by: processing a steel into a shape of a part, the steel having an alloy composition containing, by weight percent, C: 0.10 to 0.30%, Si: 0.50 to 3.00%, Mn: 0.30 to 3.00%, P: 0.030% or less, S: 0.030% or less, Cu: 0.01 to 1.00%, Ni: 0.01 to 3.00%, Cr: 0.20 to 1.00%, Al: 0.20% or less, N: 0.05% or less, and the remainder of Fe and inevitable impurities, and the alloy composition satisfying the following condition: [Si %]+[Ni %]+[Cu %]?[Cr %]>0.50, in which [Si %], [Ni %], [Cu %] and [Cr %] represent the concentration of Si, the concentration of Ni, the concentration of Cu and the concentration of Cr in the alloy composition, respectively; subjecting the steel to a carburizing treatment in a vacuum, followed by gradually cooling the steel; and subsequently subjecting the steel to a high-frequency hardening to thereby harden a surface of the steel.

Abstract: One exemplary embodiment includes a process for forming a hard carbide coating onto a low chromium-containing steel article via a chemical deposition process carried out on a particulate mix, in which molybdenum in the form of a compound FeMo or titanium in the form of a compound FeTi, or a mixture of FeMo and FeTi, may be added to the particulate mix used to form the coating.

Abstract: The invention provides a carburized part which has excellent medium-cycle fatigue strength in particular subjected to surface-hardening treatment by carburization. The invention provides a carburized part including a carburized layer formed by performing carburizing treatment to a steel, the steel including, in terms of % by mass: 0.15% to 0.25% of C, 0.15% or less of Si, 0.4% to 1.1% of Mn, 0.8% to 1.4% of Cr, 0.25% to 0.55% of Mo, 0.015% or less of P, and 0.035% or less of S, with the remainder being Fe and unavoidable impurities, and the steel satisfying the following relation; 0.10?[Mo]/(10[Si]+[Mn]+[Cr])?0.40, in which [M] represents a content of element M in terms of % by mass.

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: A method of manufacturing a gear by a skiving process, the skiving process utilizing a cutter including a rotational axis inclined to a rotational axis of a work to be processed into the gear, the skiving process feeding the cutter in a tooth trace direction of a tooth to be formed at the work in a state where the cutter rotates in synchronization with the work, the method includes a surface hardening process for hardening a work surface of the work before the skiving process is performed.

Abstract: Provided is a production method including: heating a workpiece at a temperature higher than an Ac1 transformation point in a carburizing atmosphere; slowly cooling the workpiece at not more than 70° C./Hr down to a temperature T satisfying Formula (1) while maintaining the carburizing atmosphere: Ar1?20?T(° C.)?300° C. . . . (1); and cooling the workpiece in an oxidizing atmosphere. According to this method, it is possible to efficiently produce a high-carbon chromium bearing steel whose depth of the recarburized layer or the overcarburized layer is within a range from 0 to 0.2 mm, having less machining allowance, and excellent in machinability, using a steel tube after hot tube-making.

Abstract: Steel for manufacturing cemented steel parts, characterized in that the composition thereof in weight percentages is: 0.1%?C?0.15%; 0.8%?Mn?2%; 1%?Cr?2.5%; 0.2%?Mo?0.6%; trace elements?Si?0.35%; trace elements?Ni?0.7% trace elements?B?0.005%; trace elements?Ti?0.1% trace elements?N?0.01% if 0.0005% (5 ppm)?B?0.005%, and trace elements?N?0.02% if trace elements?B?0.0005% (5 ppm); trace elements?Al?0.1%; trace elements?V?0.3%; trace elements?P?0.025%; trace elements?Cu?1%, preferably?0.6%; trace elements?S?0.1%; the remainder being iron and impurities resulting from production. A cemented steel part made with this steel, and to the method for manufacturing same.

Abstract: The present invention provides a carburized steel part obtained by subjecting a base material to a cutting operation and a carburizing operation, in which the base material includes chemical components of: C: greater than 0.3 but less than or equal to 0.6% by mass; Si: 0.01 to 1.5% by mass; Mn: 0.3 to 2.0% by mass; P: 0.0001 to 0.02% by mass; S: 0.001 to 0.15% by mass; N: 0.001 to 0.03% by mass; Al: greater than 0.06 but less than or equal to 0.3% by mass; and, O: 0.0001 to 0.005% by mass, with a balance including iron and inevitable impurities, and in which the carburized steel part has a hardness of HV550 to HV800 in a surface layer portion, and a hardness of HV400 to HV550 in a core portion.

Abstract: A case hardened gear steel having enhanced core fracture toughness includes by weight percent about 16.3Co, 7.5Ni, 3.5Cr, 1.75Mo, 0.2W, 0.11C, 0.03Ti, and 0.02V and the balance Fe, characterized as a predominantly lath martensitic microstructure essentially free of topologically close-packed (TCP) phases and carburized to include fine M2C carbides to provide a case hardness of at least about 62 HRC and a core toughness of at least about 50 ksi?in.

Abstract: A surface processing method includes the step of increasing a surface hardness of a metal having a nominal composition that includes about 0.21-0.25 wt % carbon, about 2.9-3.3 wt % chromium, about 11-12 wt % nickel, about 13-14 wt % cobalt, about 1.1-1.3 wt % molybdenum, and a balance of iron from a first hardness to a second hardness. For example, the method is used to produce a surface-hardened component that includes a core section having a first hardness between about 51 HRC and 55 HRC and a case section having a second hardness that is greater than the first hardness.

Abstract: A process for the high temperature carburization of steel comprising heating said steel in a vacuum furnace in the presence of a hydrocarbon carburizing gas in combination with hydrogen wherein said carburizing gas/hydrogen combination is administered to the vacuum furnace by cyclically reducing the pressure in the furnace followed by the pulsed addition of the hydrocarbon carburizing gas with hydrogen at partial pressure followed by a second diffusion cycle wherein the steel is further annealed for a time sufficient to allow for the additional deposition of from about 0.8% to about 3.0% m/o of said carbon onto the surface of said steel to permit the further migration of the carbon from the steel surface to the interior thereof.

Abstract: A flat steel product, intended to be formed into a component by hot press forming and having a base made of steel, onto which a metal anti-corrosion coating of a Zn or a Zn alloy is applied. A separate finishing coat is applied to at least one of the free surfaces of the flat steel product. The finishing coat includes at least one base metal compound (oxide, nitride, sulphide, sulphate, carbide, carbonate, fluoride, hydrate, hydroxide, or phosphate). Also, a method enabling the production of a flat steel product of this kind.

Abstract: A case hardening steel, which has excellent cold forgeability and excellent crystal grain coarsening prevention characteristics after carburization, contains, in mass %, 0.05-0.20% of C, 0.01-0.1% of Si, 0.3-0.6% of Mn, 0.03% or less of P (excluding 0%), 0.001-0.02% of S, 1.2-2.0% of Cr, 0.01-0.1% of Al, 0.010-0.10% of Ti, 0.010% or less of N (excluding 0%), and 0.0005-0.005% of B, with the balance consisting of iron and unavoidable impurities. The density of Ti-based precipitates having circle-equivalent diameters less than 20 nm in the case hardening steel is 10-100 pieces/?m2; the density of Ti-based precipitates having diameters of 20 nm or more in the case hardening steel is 1.5-10 pieces/?m2; and the case hardening steel has a Vickers hardness of 130 HV or less.

Abstract: A carburized steel part having excellent low cycle bending fatigue strength which is comprised of a steel material which contains, by mass %, C: 0.1 to 0.6%, Si: 0.01 to 1.5%, Mn: 0.3 to 2.0, P: 0.02% or less, S: 0.001 to 0.15%, N: 0.001 to 0.03%, Al: 0.001 to 0.06%, and O: 0.005% or less and has a balance of substantially iron and unavoidable impurities and which is carburized and quenched, and then tempered, which steel part has a surface hardness of HV550 to HV800 and a core hardness of HV400 to HV500.

Abstract: Disclosed is a carburization heat treatment method including carburizing a workpiece at a relatively low temperature within a temperature range of A1˜A3 using a vacuum carburizing furnace and then performing quenching using a high-pressure gas, in which the workpiece is made of typical carburizing alloy steel having a carbon content of about 0.10˜0.35 wt %. This method can be applied to carburization heat treatment of a steel workpiece sensitive to heat deformation, such as an annulus gear, in lieu of a conventional gas carburization method using plug quenching.

Abstract: A roller for a roller hearth furnace comprising a dispersion strengthened steel is disclosed. The roller does not require any coating or reconditioning.

Abstract: A method of processing steel includes carburizing a martensitic stainless steel work piece to produce a carburized case by utilizing in combination, (i) a composition of the martensitic stainless steel work piece, (ii) a preselected carbon concentration in the carburized case, and (iii) a preselected grain size of the martensitic stainless steel work piece such that the carburized case predominately forms carbides of composition M6C, M2C, M23C6 or combinations thereof. The martensitic stainless steel work piece is then heated to substantially solution the metal carbides. The work piece is then quenched at a cooling rate that is sufficient to avoid substantial precipitation of any carbides during cool down to the martensite start temperature, then given a low temperature temper. In so doing, the carburized case hardened martensitic stainless steel will have balanced mechanical, tribological and corrosion resistance properties for high performance bearing and gear components.

Abstract: Provided is a production method including: heating a workpiece at a temperature higher than an Ac1 transformation point in a carburizing atmosphere; slowly cooling the workpiece at not more than 70° C./Hr down to a temperature T satisfying Formula (1) while maintaining the carburizing atmosphere: Ar1?20?T(° C.)?300° C. . . . (1); and cooling the workpiece in an oxidizing atmosphere. According to this method, it is possible to efficiently produce a high-carbon chromium bearing steel whose depth of the recarburized layer or the overcarburized layer is within a range from 0 to 0.2 mm, having less machining allowance, and excellent in machinability, using a steel tube after hot tube-making.

Abstract: The invention provides a deep groove ball bearing which exhibits a long life even in a high-temperature environment or an environment involving the penetration of water in spite of its low alloying element content. The outer race, inner race and ball constituting the bearing are made of a steel which contains 0.3 to 0.4% of carbon, 0.3 to 0.7% of silicon, 0.3 to 0.8% of manganese, 0.5 to 1.2% of nickel, 1.6 to 2.5% of chromium, 0.1 to 0.7% of molybdenum and 0.2 to 0.4 of vanadium with the balance consisting of iron and impurities and in a total content of silicon and manganese of 1.0% or below, a total content of nickel and chromium of 2.3% or above and a total content of chromium, molybdenum and vanadium of 3.0% or below.

Abstract: A carburizing steel has a composition containing, in mass %, C: 0.1-0.35%; Si: 0.01-0.22%; Mn: 0.3-1.5%; Cr: 1.35-3.0%; P: 0.018% or less; S: 0.02% or less; Al: 0.015-0.05%; N: 0.008-0.015%; and O: 0.0015% or less, each being contained in an amount within a range satisfying formulas (1), (2) and (3) below, and the balance of the composition being Fe and incidental impurities, and the carburizing steel having microstructures before spheroidizing annealing such that a total microstructure proportion of ferrite and pearlite is 85% or more and an average ferrite grain size is 25 ?m or less. 3.1?{([% Si]/2)+[% Mn]+[% Cr]}?2.2 ??(1) [% C]?([% Si]/2)+([% Mn]/5)+2[% Cr]?3.0 ??(2) 2.5?[% Al]/[% N]?1.7 ??(3) [% M] represents content (in mass %) of element M.

Abstract: An iron-base sintered part having high density and totally enhanced strength, toughness and abrasion resistance, a manufacturing method of the iron-base sintered part, and an actuator are disclosed. The iron-base sintered part is formed by an iron-nickel-molybdenum-carbon-based sintered alloy, has density of 7.25 g/cm3 or more, and has a carburization quenched structure. A method for manufacturing the iron-base sintered part includes a molding process of charging a raw mixture powder of an iron-nickel-molybdenum-based metal powder and a carbon-based powder into a cavity of a molding die and compressing the raw powder in the cavity to form a consolidation body, a sintering process of sintering the consolidation body at a sintering temperature to form a sintered alloy, and a carburization quenching process of heating the sintered alloy in a carburization atmosphere and quenching the heated alloy.

Abstract: In the steel for a surface layer hardening which is treated with carburizing in a temperature range of 800° C. to 900° C., chemical composition thereof contains, by mass %, C: 0.10% to 0.60%, Si: 0.01% to 2.50%, Mn: 0.20% to 2.00%, S: 0.0001% to 0.10%, Cr: 2.00% to 5.00%, Al: 0.001% to 0.50%, N: 0.0020% to 0.020%, P: 0.001% to 0.050%, and O: 0.0001% to 0.0030%; the remaining portion thereof includes Fe and unavoidable impurities; and the total amount of Cr, Si, and Mn satisfies, by mass %, 2.0?Cr+Si+Mn?8.0.

Abstract: A steel for a carburizing and a carburized steel component having a steel portion and a carburized layer with a thickness of more than 0.4 mm to less than 2 mm which is formed on an outside of the steel portion. A chemical composition of the steel for the carburizing and the steel portion of the carburized steel component satisfies simultaneously equations of a hardness parameter, a hardenability parameter, and a TiC precipitation parameter.

Abstract: A steel for a carburizing and a carburized steel component having a steel portion and a carburized layer with a thickness of more than 0.4 mm to less than 2 mm which is formed on an outside of the steel portion. A chemical composition of the steel for the carburizing and the steel portion of the carburized steel component satisfies simultaneously equations of a hardness parameter, a hardenability parameter, and an AlN precipitation parameter.

Abstract: A steel component formed by carburizing and then induction-hardening of a steel consisting essentially of, by mass, C: minimum 0.08% and less than 0.3%; Si: maximum 2.0%; Mn: from 0.2% to 3.0%; P: maximum 0.03%; S: from 0.005% to 0.05%; Ni: maximum 1.5%; Cr: maximum 3.0%; Mo: maximum 1.0%; O: maximum 0.0025%; and N: from 0.005% to 0.03%; and further including either or both of, by mass, Al: from 0.005% to 0.05%, and Ti: from 0.005% to 0.05%; and still further including either or both of, by mass, V: maximum 0.3%, and Nb: maximum 0.3%; and a balance including Fe and unavoidable impurities. The hardness of the surface layer is at least 55 HRC and the hardness of the core portion is from 20 to 50 HRC. The core portion does not include a martensite structure.

Abstract: The present invention is directed to a process for tempering steel comprising carburizing said steel in a vacuum furnace in the presence of a hydrocarbon carburizing gas in combination with hydrogen wherein said carburizing gas/hydrogen combination is administered to the vacuum furnace by cyclically reducing the pressure in the furnace followed by the pulsed addition of the hydrocarbon carburizing gas consisting of an acetylene/hydrogen mixture is in a ratio of from about 1:1 to about 1:10 to replenish the air removed in the pressure reduction step.

Abstract: The invention relates to a method for producing a cylinder jacket, comprising the following steps: producing a cylindrical starting product from a steel material having a carbon content of not more than 0.8% by weight and a ferritic or ferritic/pearlitic structure; enriching, by carburization, the surface layer of the inner peripheral surface of the cylindrical starting product with carbon in the form of carbides that are deposited on the grain boundaries; slowly cooling the cylindrical starting product in such a manner that a pearlitic structure having a carbide network is formed in the surface layer; finishing the cylindrical starting product to give a cylinder jacket. The invention also relates to a cylinder jacket produced by said method.