Abstract: A magnetic sheet according to the present invention contains Mn—Zn ferrite as a main component and is comprising of a sheet-shaped sintered body. In this magnetic sheet, a difference |?s??c| between a residual stress ?s in a surface layer portion and a residual stress ?c in a central portion at a cross section is 20 MPa or less in absolute value.

Abstract: A magnetic sheet according to the present invention contains Mn—Zn ferrite as a main component and is comprising of a sheet-shaped sintered body. In this magnetic sheet, a difference |?s??c| between a residual stress ?s in a surface layer portion and a residual stress ?c in a central portion at a cross section is 20 MPa or less in absolute value.

Abstract: Provided is a high-strength seamless stainless steel pipe for oil country tubular goods which possesses a high strength, excellent low-temperature toughness and excellent corrosion resistance even when the steel pipe has a large wall thickness. The high-strength seamless stainless steel pipe has the composition which contains, by mass %, C: 0.05% or less, Si: 1.0% or less, Mn: 0.1 to 0.5%, P: 0.05% or less, S: less than 0.005%, Cr: more than 15.0% to 19.0% or less, Mo: more than 2.0% to 3.0% or less, Cu: 0.3 to 3.5%, Ni: 3.0% or more and less than 5.0%, W: 0.1 to 3.0%, Nb: 0.07 to 0.5%, V: 0.01 to 0.5%, Al: 0.001 to 0.1%, N: 0.010 to 0.100%, O: 0.01% or less, and Fe and unavoidable impurities as a balance. Nb, Ta, C, N and Cu satisfy a specified formula. The steel pipe has a microstructure which is formed of 45% or more of a tempered martensite phase, 20 to 40% of a ferrite phase, and more than 10% and 25% or less of a residual austenite phase in terms of volume ratio.

Abstract: Provided herein is a high-strength seamless stainless steel pipe. The high-strength seamless stainless steel pipe contains, in mass %, C: 0.05% or less, Si: 0.5% or less, Mn: 0.15 to 1.0%, P: 0.030% or less, S: 0.005% or less, Cr: 14.5 to 17.5%, Ni: 3.0 to 6.0%, Mo: 2.7 to 5.0%, Cu: 0.3 to 4.0%, W: 0.1 to 2.5%, V: 0.02 to 0.20%, Al: 0.10% or less, N: 0.15% or less, and the balance being Fe and unavoidable impurities. C, Si, Mn, Cr, Ni, Mo, Cu, and N satisfy a specific formula. Cu, Mo, W, Cr, and Ni satisfy another specific formula. The high-strength seamless stainless steel pipe has more than 45% martensite phase, 10 to 45% ferrite phase, and 30% or less retained austenite phase. The total amount of precipitated Cr, precipitated Mo, and precipitated W is 0.75 mass % or less.

Abstract: A high-strength heavy-walled stainless steel seamless tube or pipe exhibiting excellent low-temperature toughness is characterized by having a chemical composition containing Cr: 15.5% to 18.0% and a steel microstructure containing a ferritic phase and a martensitic phase, wherein the maximum value of the areas of the ferrite grains in the steel microstructures in a circumferential direction cross section and an L direction (rolling direction) cross section of the steel tube or pipe is 3,000 ?m2 or less and the content of ferrite grains having areas of 800 ?m2 or less is 50% or more on an area fraction basis, where, when adjacent ferrite grains are present in the steel microstructure and the crystal misorientation between one ferrite grain and the other ferrite grain is 15° or more, the adjacent grains are assumed to be grains different from each other.

Abstract: A process for producing a high-grade steel tube includes the steps of: providing a tubular blank of an austenitic high-grade steel, wherein the high-grade steel comprises in weight % no more than 0.02% carbon, no more than 1.0% manganese, no more than 0.03% phosphor, no more than 0.015% sulfur, no more than 0.8% silicon, no more than 17.5% t to 18.5% nickel, no more than 19.5% to 20.5% chromium, no more than 6.0% to 6.5% molybdenum, no more than 0.18% to 0.25% nitrogen, no more than 0.5% to 1.0% copper, and a remainder of iron and unavoidable impurities; and cold-forming the blank into a tube.

Abstract: A method of manufacturing a component from a nickel-based superalloy comprises the steps of: providing a vacuum induction casting furnace; positioning a component mould onto a chill plate within the furnace; casting a component blank; peening the surface of the component blank; applying a surface modification technique to the surface of the component blank; solution heat treating the component blank at or above the ??-solvus temperature for the superalloy; and precipitation heat treating the component blank.

Abstract: A method for manufacturing a superior 13Cr thickened drillrod comprises the following steps: firstly, thickening the ends of a steel tube with a composition so as to obtain a drillrod with thickened ends, the composition in percentage by weight being: C: 0.01-0.05%, Si?0.5%, Mn: 0.2-1.0%, Cr: 12-14%, Mo: 1-3%, Ni: 4-6%, and a balance of Fe and inevitable impurities; after heating the tube as a whole to 950-1000° C., air cooling same and tempering same at 600-650° C.; and machining the two thickened ends respectively into an externally threaded drillrod coupler and an internally threaded drillrod coupler; wherein the tube end thickening is an external thickening, including three rounds of heating and three rounds of thickening, with at least one pass of deformation for each round, and the heating temperature being 1150-1200° C.

Abstract: A thermal mechanical treatment method includes consolidating a powder by a severe plastic deformation process and ageing the consolidated powder at low temperature. The method may include cryomilling the powder before consolidating the powder by a severe plastic deformation process; hot isostatic pressing the consolidated powder into a dense powder before aging the consolidated powder; hot extruding the dense powder into a stock shape before aging the consolidated powder; hot-working the stock shape on a gyrating forge at a predetermined temperature before aging the consolidated powder; or heating the consolidated powder to a predetermined temperature, and maintaining the consolidated powder at the predetermined temperature for a predetermined time.

Abstract: The invention relates to a method for producing martensitic steel that comprises a content of other metals such that the steel can be hardened by an intermetallic compound and carbide precipitation, with an Al content of between 0.4% and 3%, comprising the following steps: (a) heating the entirety of the steel above its austenizing temperature, (b) cooling said steel approximately to ambient temperature, (c) placing said steel in a cryogenic medium. The temperature T1 is substantially lower than the martensitic transformation temperature Mf, and the time t during which said steel is kept in said cryogenic medium at a temperature T1 from the moment when the hottest part of the steel reaches a temperature lower than the martensitic transformation temperature Mf is at least equal to a non-zero time t1, the temperature T1 (in ° C.

Abstract: A stainless steel for oil wells which has excellent high-temperature corrosion resistance and can stably obtain a strength of not less than 758 MPa is provided. The stainless steel for oil wells contains, by masse, C: not more than 0.05%, Si: not more than 1.0%, Mn: 0.01 to 1.0%, P: not more than 0.05%, S: less than 0.002%, Cr: 16 to 18%, Mo: 1.8 to 3%, Cu: 1.0 to 3.5%, Ni: 3.0 to 5.5%, Co: 0.01 to 1.0%, Al: 0.001 to 0.1%, O: not more than 0.05%, and N: not more than 0.05%, the balance being Fe and impurities, and satisfies Formulas (1) and (2): Cr+4Ni+3Mo+2Cu?44??(1) Cr+3Ni+4Mo+2Cu/3?46??(2) where each symbol of element in Formulas (1) and (2) is substituted by the content (mass %) of a corresponding element.

Abstract: A pipe having chemical composition contains, by mass %, C: 0.05% or less, Si: 0.5% or less, Mn: 0.15% or more and 1.0% or less, Cr: 13.5% or more and 15.4% or less, Ni: 3.5% or more and 6.0% or less, Mo: 1.5% or more and 5.0% or less, Cu: 3.5% or less, W: 2.5% or less, and N: 0.15% or less so that the relationship ?5.9×(7.82+27C?0.91 Si+0.21Mn?0.9Cr+Ni?1.1Mo?0.55W+0.2Cu+11N)?13.0 is satisfied.

Abstract: A high-strength stainless steel for oil well having corrosion resistance excellent in a high-temperature environment, having excellent SSC resistance at normal temperature, and having better workability than 13% Cr steels has a chemical composition containing, by mass percent, C: at most 0.05%, Si: at most 1.0%, Mn: at most 0.3%, P: at most 0.05%, S: less than 0.002%, Cr: over 16% and at most 18%, Mo: 1.5 to 3.0%, Cu: 1.0 to 3.5%, Ni: 3.5 to 6.5%, Al: 0.001 to 0.1%, N: at most 0.025%, and O: at most 0.01%, the balance being Fe and impurities, a microstructure containing a martensite phase, 10 to 48.5%, by volume ratio, of a ferrite phase and at most 10%, by volume ratio, of a retained austenite phase, yield strength of at least 758 MPa and uniform elongation of at least 10%.

Abstract: The chemical composition of a stainless steel in accordance with the present invention consists of C: not more than 0.05%, Si: not more than 0.5%, Mn: 0.01 to 0.5%, P: not more than 0.04%, S: not more than 0.01%, Cr: more than 16.0 and not more than 18.0%, Ni: more than 4.0 and not more than 5.6%, Mo: 1.6 to 4.0%, Cu: 1.5 to 3.0%, Al: 0.001 to 0.10%, and N: not more than 0.050%, the balance being Fe and impurities, and satisfies Formulas (1) and (2). Also, the micro-structure thereof contains a martensitic phase and a ferritic phase having a volume ratio of 10 to 40%, and the ferritic phase distribution ratio is higher than 85%. Cr+Cu+Ni+Mo?25.5??(1) ?8?30(C+N)+0.5Mn+Ni+Cu/2+8.2?1.

Abstract: In a method for heat treating a metal tube or pipe for a nuclear power plant, the tube or pipe being accommodated in a batch-type vacuum heat treatment furnace, when the tube or pipe is laid down on and is subjected to heat treatment on a plurality of metal cross beams arranged along a longitudinal direction of the tube or pipe, it is possible to suppress scratches to be formed on the outer surface of the tube or pipe and attributable to heat treatment, and to reduce the discoloration on the outer surface of the tube or pipe by holding the tube or pipe and the metal cross beams in indirect contact with each other by virtue of a heat resistant fabric having a thickness of 0.1 to 1.2 mm interposed in between.

Abstract: Methods to enhance the quality of grain boundary networks are described. The process can result in the production of a metal including a relatively large fraction of special grain boundaries (e.g., a fraction of special grain boundaries of at least about 55%).

Abstract: The present invention provides a thick welded steel pipe excellent in low temperature toughness in which contents of Mn and Mo satisfy (Expression 1) below, Pcm obtained by (Expression 2) below is 0.16 to 0.19, and a metal structure of a base material steel plate consists of ferrite being 30 to 95% in an area ratio and a low temperature transformation structure, and in a metal structure of a coarse-grained HAZ, an area ratio of grain boundary ferrite is 1.5% or more, the total area ratio of the grain boundary ferrite and intragranular ferrite is not less than 11% nor more than 90%, an area ratio of MA is 10% or less, and its balance is composed of bainite. 1.2325?(0.85×[Mn]?[Mo])?1.5215??(Expression 1) and Pcm=[C]+[Si]/30+([Mn]+[Cu]+[Cr])/20+[Ni]/60+[Mo]/15+[V]/10??(Expression 2).

Abstract: In a method for heat treating a metal tube or pipe for a nuclear power plant, the tube or pipe being accommodated in a batch-type vacuum heat treatment furnace, when the tube or pipe is laid down on and is subjected to heat treatment on a plurality of metal cross beams arranged along a longitudinal direction of the tube or pipe, it is possible to suppress scratches to be formed on the outer surface of the tube or pipe and attributable to heat treatment, and to reduce the discoloration on the outer surface of the tube or pipe by holding the tube or pipe and the metal cross beams in indirect contact with each other by virtue of a heat resistant fabric having a thickness of 0.1 to 1.2 mm interposed in between.

Abstract: An Fe—Ni alloy pipe stock containing, by mass %, C?0.04%, Si?0.50%, Mn: 0.01 to 6.0%, P?0.03%, S?0.01%, Cr: 20 to 30%, Ni: 30 to 45%, Mo: 0 to 10%, W: 0 to 20%, with Mo(%)+0.5W(%): more than 1.5% to not more than 10%, Cu: 0.01 to 1.5%, Al?0.01% and N: 0.0005 to 0.20%, and the balance being Fe, with 1440?6000P?100S?2000C?1300, Ni+10(Mo+0.5W)+100N?120, (Ni?35)+10(N?0.1)?2(Cr?25)?5(Mo+0.5W?3)+8?0, can be manufactured into a seamless pipe by use of a Mannesmann piercing and rolling mill because of its excellent inner surface properties. The resulting seamless pipe has excellent mechanical properties and moreover has excellent corrosion resistance in a sour gas environment.

Abstract: The present invention is to provide a method for producing duplex stainless steel seamless pipe in which a duplex stainless steel billet can be inhibited from generating an oxide scale on the surface thereof during heating and the generation of outer surface flaw can also be prevented. The billet is heated in the a heating furnace for 1.5 hours or more and 4.0 hours or less at a heating temperature of 1250° C. or more and 1320° C. or less while regulating the average concentration of sulfur dioxide (SO2) gas in the atmosphere within the furnace to 0.01 volume % or less.

Abstract: A method of producing a seamless, tubular product includes centrifugally casting a corrosion resistant alloy into a tubular workpiece having an inner diameter and an outer diameter. The method then removes material from the inner diameter of the workpiece and subjects the workpiece to at least about a 25% wall reduction at a temperature below a recrystallization temperature of the workpiece using a metal forming process. The metal forming process includes radial forging, rolling, pilgering, and/or flowforming.

Abstract: A method of manufacturing a 13Cr steel pipe which satisfies a hardness (HRC) of at most 22 with 13Cr grade L80 of American Petroleum Institute (API) standards, which is an indicator of a high strength, high yield ratio, and good corrosion resistance, is provided. A steel billet having a chemical composition comprising, in mass percent, C: 0.15-0.21%, Si: 0.16-1.0%, Mn: 0.35-1.0%, Cr: 10.5-14.0%, P: at most 0.020%, S: at most 0.0050%, Al: 0.025-0.050%, and a remainder of Fe and impurities is subjected to hot working with a finishing temperature of 800-960° C. to form a mother pipe, which is immediately quenched at a cooling rate of at least air cooling and then tempered by heating.

Abstract: A method for producing a two-phase stainless steel pipe, which comprises: preparing a two-phase stainless steel material consisting of, by mass %, C: 0.03% or less, Si: 1% or less, Mn: 0.1 to 2%, Cr: 20 to 35%, Ni: 3 to 10%, Mo: 0 to 4%, W: 0.5 to 6%, Cu: 0 to 3% and N: more than 0.175 and up to 0.35%, and the balance being Fe and impurities; forming a material pipe by subjecting to a hot working: and performing a cold drawing, where the cold drawing is characterized in being performed under the conditions that the working ratio Rd, in terms of the reduction of area, in the final cold drawing step is within a range from 5 to 35%, and the following formula (1) is satisfied: Rd(%)?(MYS?55)/17.2?{1.2×Cr+3.0×(Mo+0.5×W)}??(1).

Abstract: A method for producing a duplex stainless steel pipe having a minimum yield strength of 758.3 to 965.2 MPa, comprises first hot working and optionally solution heat treating a duplex stainless steel material pipe having a chemical composition consisting, by mass %, of C: 0.03% or less, Si: 1% or less, Mn: 0.1 to 4%, Cr: 20 to 35%, Ni: 3 to 10%, Mo: 0 to 6%, W: 0 to 6%, Cu: 0 to 3% and N: 0.15 to 0.60%, the balance being Fe and impurities. The pipe is then cold rolled under conditions that the working ratio Rd, in terms of the reduction of area, in the final cold rolling step falls within a range from 10 to 80%, and formula (1) is satisfied: Rd=exp[{In(MYS)?In(14.5×Cr+48.3×Mo+20.7×W+6.9×N)}/0.195]??(1) wherein Rd is a reduction in area %, MYS is the targeted yield strength (MPa), and Cr, Mo, W and N are in mass %.

Abstract: There are provided an austenitic stainless steel having high stress corrosion crack resistance, characterized by containing, in percent by weight, 0.030% or less C, 0.1% or less Si, 2.0% or less Mn, 0.03% or less P, 0.002% or less S, 11 to 26% Ni, 17 to 30% Cr, 3% or less Mo, and 0.01% or less N, the balance substantially being Fe and unavoidable impurities; a manufacturing method for an austenitic stainless steel, characterized in that a billet consisting of the said austenitic stainless steel is subjected to solution heat treatment at a temperature of 1000 to 1150° C.; and a pipe and a in-furnace structure for a nuclear reactor to which the said austenitic stainless steel is applied.

Abstract: The method for manufacturing a martensitic stainless pipe includes heating the steel pipe until the external surface temperature thereof reaches a predetermined temperature not lower than A3 transformation point+20° C. and not higher than 980° C. The heated steel pipe is first water cooled until the external surface temperature thereof reaches a predetermined temperature not lower than 350° C. The water cooled steel pipe is air cooled until the external surface temperature thereof reaches a predetermined temperature not higher than 250° C. The air cooled steel pipe is either water or air cooled until the external surface temperature thereof reaches normal temperature. The cooling rate of the steel pipe in the first cooling step is determined according to the wall thickness of the steel pipe so that the amount of heat recuperation for the external surface temperature of the steel pipe in the second cooling step is not higher than 50° C.

Abstract: A method for producing a high-strength Cr—Ni alloy seamless pipe comprising preparing an alloy billet with a chemical composition consisting, by mass %, of C: 0.05% or less, Si: 1.0% or less, Mn: less than 3.0%, P: 0.005% or less, S: 0.005% or less, Cu: 0.01 to 4.0%, Ni: 25% or more and less than 35%, Cr: 20 to 30%, Mo: 0.01% or more and less than 4.0%, N: 0.10 to 0.30%, Al: 0.03 to 0.30%, O (oxygen): 0.01% or less, REM (rare earth metal): 0.01 to 0.20%, and the balance being Fe and impurities, and satisfying the formula N×P/REM?0.10, wherein P, N and REM represent the contents (mass %) of P, N and REM, respectively. The pipe is hot worked using cross roll piercing, solution heat treated, and cold worked. The pipe is excellent in hot workability, stress corrosion cracking and does not laminate during cross piercing.

Abstract: A stainless steel material for a fuel cell, used for a fuel cell or a cartridge for the fuel cell, having a magnetic permeability of 1.000 to 2.500, and forming a layer having a value of chromium atomic %/iron atomic % of not less than 3.0 in the most surface thereof, and/or the layer of thickness of not less than 12 nm calculated as SiO2 having an oxygen atomic % of not less than 20%. Even when brought into contact with the content solution exhibiting acidity of the fuel cell, the stainless steel material reliably suppresses the elution of metal ions thereof.

Abstract: A steel pipe is prepared, which contains, by mass, at most 0.009% C, at most 1.0% Mn, at most 1.0% Si, at most 0.04% P, at most 0.005% S, 0.01 to 0.2% Ti, 0.01 to 0.10% V, 0.001 to 0.1% Al, at most 0.1% N, 4.0 to 8.0% Ni, 9.0 to 15.0% Cr, and 1.5 to 7.0% Mo, the balance being Fe and impurities. The prepared steel pipe is bent into a bend pipe. The bend pipe is quenched at a quenching temperature lower than 950° C. The quenched bend pipe is tempered. Accordingly, the bend pipe in accordance with the present invention has excellent SSC resistance.

Abstract: The present invention relates to an austenitic stainless steel tube for boiler, used for superheater or reheater in thermal power plant, giving excellent resistance to high temperature steam oxidation, in particular to an austenitic stainless steel tube containing 16 to 20% Cr by weight, and being cold-worked at the inner surface of the tube. The Cr concentration in the vicinity of the inner surface of the steel tube is 14% by weight or larger, and the hardness at 100 ?m depth from the inner surface of the steel tube is 1.5 times or larger the average hardness of the mother material or is HV 300 or larger.

Abstract: A martensitic stainless steel pipe, which comprises specified quantities of C, Si, Mn, P, S, Cr, Ni, Al, N, Cu, Ti, V, Mo, Nb, B and Ca, and the balance being Fe and impurities, has satisfactory toughness at a high strength of 650 MPa or more by yield strength and also excellent hot workability. Therefore, it can be used as a high-strength martensitic stainless steel pipe for carbon dioxide gas corrosion resistant use, to be used in oil and/or gas well environments containing no hydrogen sulfide but carbon dioxide gas. This high-strength martensitic stainless steel pipe is an inexpensive martensitic stainless steel pipe, which does not require an addition of large quantities of expensive elements such as Ni and Mo, and moreover does not require the control of the content of P to a value less than 0.010% by mass.

Abstract: A martensitic stainless steel seamless tube for oil country tubular goods includes a yield strength of 95 ksi or more and low-temperature toughness in which a fracture transition temperature vTrs in a Charpy impact test is ?40° C. or below, wherein the seamless tube has a composition comprising, by mass %, 0.020% or less C, 10 to 14% Cr, 3% or less Ni, 0.03 to 0.2% Nb, 0.05% or less N, and Fe and unavoidable impurities as a balance, and has a structure where a precipitated Nb quantity is 0.020% or more in terms of Nb.

Abstract: A method for making gas and liquid storage tanks such as automotive fuel tanks includes providing two or more blanks of air hardenable martensitic stainless steel in the annealed condition. The steel blanks have a thickness in the range of 0.5-5.0 mm., and are formed utilizing stamping, forging, pressing, or roller forming techniques or the like into the form of a tank shell components. The shell components are hardened and assembled into a storage tank. The shell components are hardened by application of heat, preferably to between 950° C. and 1100° C. for standard air hardenable martensitic stainless steels. Thereafter, the automotive fuel tank is preferably cooled at a rate greater than 25° C. per minute to achieve a Rockwell C hardness of at least 39. The automotive fuel tank may undergo additional heat treating processes including high temperature or low temperature tempering processes which may incorporate electro-coating.

Abstract: A two-phase stainless steel pipe that has not only a corrosion resistance required for oil well pipes but at the same time has a targeted strength is produced, without excessively adding alloying components, by selecting cold drawing conditions. A method for producing a two-phase stainless steel pipe, which comprises, preparing a two-phase stainless steel material having a chemical composition that consists of, by mass %, C: 0.03% or less, Si: 1% or less, Mn: 0.1 to 2%, Cr: 20 to 35%, Ni: 3 to 10%, Mo: 0 to 4%, W: 0 to 6%, Cu: 0 to 3% and N: 0.15 to 0.35%, and the balance being Fe and impurities, forming a material pipe by subjecting to a hot working or further a solid-solution heat treatment, and performing a cold drawing, where the cold drawing is characterized in being performed under the conditions that the working ratio Rd, in terms of the reduction of area, in the final cold drawing step is within a range from 5 to 35%, and the following formula (1) is satisfied: Rd(%)?(MYS?55)/17.2?{1.2×Cr+3.0×(Mo+0.

Abstract: A highly corrosion resistant high strength stainless steel pipe for linepipe, having a composition containing about 0.001 to about 0.015% C, about 0.01 to about 0.5% Si, about 0.1 to about 1.8% Mn, about 0.03% or less P, about 0.005% or less S, about 15 to about 18% Cr, about 0.5% or more and less than about 5.5% Ni, about 0.5 to about 3.5% Mo, about 0.02 to about 0.2% V, about 0.001 to about 0.015% N, and about 0.006% or less O, by mass, so as to satisfy (Cr+0.65 Ni +0.6Mo+0.55Cu?20C?18.5), (Cr+Mo+0.3Si?43.5C?0.4Mn?Ni?0.3Cu?9 N?11.5) and (C+N?0.025). Preferably quenching and tempering treatment is applied to the pipe. The composition may further contain about 0.002 to about 0.05% Al, and may further contain one or more of Nb, Ti, Zr, B, and W, and/or Cu and Ca. The microstructure preferably contains martensite, ferrite, and residual ?.

Abstract: A seamless steel pipe for oil country tubular goods which simultaneously has a high strength of a 110 ksi grade of yield strength and a superior low temperature toughness and a method for manufacturing the same are provided. A quenching treatment is performed on a stainless steel seamless pipe having a composition which contains on a mass percent basis, less than 0.010% of C, 1.0% or less of Si, 0.1% to 2.0% of Mn, 0.020% or less of P, 0.010% or less of S, 0.10% or less of Al, 10% to 14% of Cr, 0.1% to 4.0% of Ni, 0.05% or less of N, and the balance being Fe and inevitable impurities in which after heating is performed to a heating temperature for quenching equivalent to or more than the Ac3 transformation point, cooling is performed to a temperature range of 100° C. or less at a cooling rate equivalent to or more than that of air cooling; and following the quenching treatment, a tempering treatment is performed in which heating is performed to a tempering temperature in the range of more than 450° C.

Abstract: The present invention provides a martensitic stainless steel seamless pipe and a method of making, wherein the pipe has minimal inner surface defects and prevents delayed fracture generation in the impact-worked portions. The pipe comprises C: 0.15 to 0.22%, Si: 0.1 to 1.0%, Mn: 0.10 to 1.00%, Cr: 12.00 to 14.00%, P: 0.020% or less, S: 0.010% or less, N: 0.05% or less, O(Oxygen): 0.0060% or less, at least one alloying element selected from V, Nb and Ti of 0.005 to 0.200% and B of 0.0005 to 0.0100%, and the balance Fe and impurities, wherein either the following inequalities (1), (2), (4) and (5) or the following inequalities (1), (3), (4) and (5) are satisfied: C*+10N*?0.45,??(1) H1??0.003(C*+10N*)+0.0016,??(2) H2??0.0018(C*+10N*)+0.00096,??(3) Cr*?9.0,??(4) S?0.088N*+0.00056,??(5).

Abstract: A steel pipe is prepared, which contains, by mass, at most 0.009% C, at most 1.0% Mn, at most 1.0% Si, at most 0.04% P, at most 0.005% S, 0.01 to 0.2% Ti, 0.01 to 0.10% V, 0.001 to 0.1% Al, at most 0.1% N, 4.0 to 8.0% Ni, 9.0 to 15.0% Cr, and 1.5 to 7.0% Mo, the balance being Fe and impurities. The prepared steel pipe is bent into a bend pipe. The bend pipe is quenched at a quenching temperature lower than 950° C. The quenched bend pipe is tempered. Accordingly, the bend pipe in accordance with the present invention has excellent SSC resistance.

Abstract: A production system weldable and stainless tubular structures with high mechanical strength and related obtained product, particularly for making tubular elements in cold-drawn stainless steel, workable at different thicknesses and shapes, provided with high performances in terms of mechanical characteristics and weldability, for the construction of light and ultralight structural frames destined for a dynamic use. It comprises a creation step of a tip for making the end of the tube smaller, so that it can pass through the drawing equipment and be coupled for drawing, a step of annealing heat treatment for softening the material and making it deformable.

Abstract: A steel composition contains: 0.05% or less of C; 0.5% or less of Si; 0.20% to 1.80% of Mn; 0.03% or less of P; 0.005% or less of S; 14.0% to 18.0% of Cr; 5.0% to 8.0% of Ni; 1.5% to 3.5% of Mo; 0.5% to 3.5% of Cu; 0.05% or less of Al; 0.20% or less of V; 0.01% to 0.15% of N; and 0.006% or less of O on a mass basis, and satisfies the following expressions: Cr+0.65Ni+0.6Mo+0.55Cu?20C?18.5 and Cr+Mo+0.3Si?43.5C?0.4Mn?Ni?0.3Cu?9N?11 (where Cr, Ni, Mo, Cu, C, Si, Mn, and N represent their respective contents (mass %)). After such a steel pipe material is formed into a steel pipe, the steel pipe is quenched by cooling after heating to a temperature of the AC3 transformation point or more and tempered at a temperature of the AC1 transformation point or less. The composition may further contain at least one element of Nb and Ti; at least one element selected from the group consisting of Zr, B, and W; or Ca, singly or in combination.

Abstract: The present invention relates to an austenitic stainless steel tube for boiler, used for superheater or reheater in thermal power plant, giving excellent resistance to high temperature steam oxidation, in particular to an austenitic stainless steel tube containing 16 to 20% Cr by weight, and being cold-worked at the inner surface of the tube. The Cr concentration in the vicinity of the inner surface of the steel tube is 14% by weight or larger, and the hardness at 100 ?m depth from the inner surface of the steel tube is 1.5 times or larger the average hardness of the mother material or is HV 300 or larger.

Abstract: A martensitic stainless steel pipe, which comprises specified quantities of C, Si, Mn, P, S, Cr, Ni, Al, N, Cu, Ti, V, Mo, Nb, B and Ca, and the balance being Fe and impurities, has satisfactory toughness at a high strength of 650 MPa or more by yield strength and also excellent hot workability. Therefore, it can be used as a high-strength martensitic stainless steel pipe for carbon dioxide gas corrosion resistant use, to be used in oil and/or gas well environments containing no hydrogen sulfide but carbon dioxide gas. This high-strength martensitic stainless steel pipe is an inexpensive martensitic stainless steel pipe, which does not require an addition of large quantities of expensive elements such as Ni and Mo, and moreover does not require the control of the content of P to a value less than 0.010% by mass.

Abstract: In a martensitic stainless steel tube according to the present invention, the content is determined by each of elements C, Si, Mn and Cr, and the bubble content ratio is further prescribed in accordance with the scale thickness on the outer surface of the steel tube, so that defects can be detected with high precision in the non-destructive inspection, such as ultrasonic test or the like. This allows the non-destructive inspection to be carried out with high efficiency. Moreover, there is another advantage that the weather resistance can be enhanced. The steel tube according to the present invention and the manufacturing method thereof can be suitably used in all of the technical fields in which a martensitic stainless steel tube having equal chemical composition is treated.

Abstract: A method for making structural automotive components and the like includes providing a blank of air hardenable martensitic stainless steel in the annealed condition. The steel blank has a thickness in the range of 0.5-5.0 mm., and is formed utilizing stamping, forging, pressing, or roller forming techniques or the like into the form of an automotive structural member. The automotive structural member is then hardened by application of heat, preferably to between 950° C. and 1100° C. for standard martensitic stainless steels. Thereafter, the automotive structural member is preferably cooled at a rate greater than 25° C. per minute to achieve a Rockwell C hardness of at least 39. The automotive structural member may undergo additional heat treating processes including high temperature or low temperature tempering processes which may incorporate electro-coating.

Abstract: A martensitic alloy in which the ASTM grain size number is at least 5, including (wt. %) up to about 0.5% C, at least about 5% Cr, at least about 0.5% Ni, up to about 15% Co, up to about 8% Cu, up to about 8% Mn, up to about 4% Si, up to about 6% (Mo+W), up to about 1.5% Ti, up to about 3% V, up to about 0.5% Al, and at least about 40% Fe.

Abstract: A metallic bellows, composed of precipitation hardening stainless steel, includes ridge portions and valley portions formed alternately and continuously, an average grain size of 10 to 15 ?m, and compressive residual stress of not less than 500 MPa provided to at least surfaces of the ridge portions and the valleys by surface working.

Abstract: This invention relates to a welded line pipe structure for transporting corrosive petroleum or natural gas. It is constituted by martensitic stainless steel pipes containing 8–16% Cr and at most 0.05% C. By suitably controlling the welding conditions at the time of girth welding of the steel pipes so as to ensure that the Cr concentration in grain boundary Cr-depleted portions existing immediately beneath a weld oxide scale is at least 5%, the occurrence of SCC in a high temperature CO2 environment can be prevented.

Abstract: The present invention provides seam-welded, air hardenable steel tubes, methods of manufacturing seam-welded air hardenable steel tubes, tube mills for practicing such methods and applications for using seam-welded, air hardenable steel tubing of the present invention.

Abstract: A method for manufacturing a seamless steel tube, wherein a tubing material for the seamless steel tube is produced by a hot working process from a material having less workability, such as a high Cr—high Ni—high C alloy steel including Cr at a content not less than 15 weight % and Ni at a content not less than 20 weight % or a ferritic stainless steel including Cr at a content not less than 16 weight %, and then cold drawn at a reduction rate of not less than 15% and further cold rolled after applying an appropriate heat treatment, so that a round or an inner grooved steel tube is obtained. It is preferable that the hot extrusion process is employed for the hot working process and a cold Pilger mill is employed for the cold rolling process. In the cold rolling process, the crackings or damage resulting from the reduced toughness of the tubing material as well as the breakage of a mandrel in producing the round or the inner grooved tube can be suppressed.

Abstract: A new surface finishing process for stainless steel where beautiful, bright and milky white coloured surface is obtainable even for such grades as high carbon containing 13 chromium steel and high sulfur containing free cutting stainless steel is disclosed. After removing the surface scale, (1) immerse the stainless steel into the 1st treating solution containing nitric acid: 5–40 g/l, hydrofluoric acid: 2–10 g/l and Fe(III) ion: 15–40 g/l for 5–180 sec., then rinse in water, (2) and successesively immerse into the 2nd treating solution containing nitric acid: 120–250 g/l, Fe(III) ion: 15–40 g/l for 30–300 sec., then rinse in water.