Abstract: Techniques for using additive manufacturing (AM) to fabricate creep resistant ferritic/martensitic steel with improved high temperature strength are described. AM processing may be performed on Grade 91 steel powder. Beam powers from about 221 W to about 270 W may be used. Traverse rates from about 675 mm/s to about 825 mm/s may be used. Heat inputs ranging from about 55.7 J/mm3 to about 83.2 J/mm3 may be produced. Creep resistant ferritic/martensitic steel, produced according to the present disclosure, has improved strain yield strength and ductility as compared to wrought steel.

Abstract: An aspect of the present disclosure relates to a high-strength steel material having enhanced resistance to crack initiation and propagation at low temperature.

Abstract: The invention relates to a bainite steel consisting of the following elements in weight %: C: 0.25-0.55 Si: 0.5-1.8 Mn: 0.8-3.8 Cr: 0.2-2.0 Ti: 0.0-0.1 Cu: 0.0-1.2 V: 0.0-0.5 Nb: 0.0-0.06 Al: 0.0-2.75 N: <0.004 P: <0.025 S: <0.025 and a method for manufacturing a bainite steel strip that comprises the step of cooling the coiled strip of such composition to ambient temperature, during which the bainite transformation takes place.

Abstract: There are provided a ferrite stainless steel for a polymer fuel cell separator having excellent corrosion resistance and interfacial contact resistance under an operating environment of a polymer fuel cell, and a preparation method of the stainless steel. A stainless steel includes C: 0.02 wt % or less, N: 0.02 wt % or less, Si: 0.4 wt % or less, Mn: 0.2 wt % or less, P: 0.04 wt % or less, S: 0.02 wt % or less, Cr: 25.0 to 32.0 wt %, Cu: 0 to 2.0 wt %, Ni: 0.8 wt % or less, Ti: 0.5 wt % or less, Nb: 0.5 wt % or less, waste Fe and inevitably contained elements. A preparation method of the stainless steel having a second passive film formed on a surface thereof includes forming a first passive film on the surface of the stainless steel by bright-annealing or annealing-pickling the stainless steel; removing the first passive film by pickling the stainless steel in a 10 to 20 wt % sulfuric acid solution at a temperature of 50 to 75° C.

Abstract: An abrasion-resistant steel plate comprises: a specific chemical composition; and a microstructure in which a volume fraction of martensite at a depth of 1 mm from a surface of the abrasion-resistant steel plate is 90% or more, and a prior austenite grain size at the mid-thickness of the abrasion-resistant steel plate is 80 ?m or less, wherein hardness at a depth of 1 mm from the surface of the abrasion-resistant steel plate is 360 to 490 HBW 10/3000 in Brinell hardness, and a concentration [Mn] of Mn in mass % and a concentration [P] of P in mass % in a plate thickness central segregation area satisfy 0.04[Mn]+[P]<0.55.

Abstract: A process of producing a duplex stainless steel tube comprises the steps of: a) producing an ingot or a continuous casted billet of said duplex stainless steel; b) hot extruding the ingot or the billet obtained from step a) into a tube; and c) cold rolling the tube obtained from step b) to a final dimension thereof. The outer diameter D and the wall thickness t of the cold rolled tube is 50-250 mm respectively is 5-25 mm, and, for the cold rolling step, R and Q are set such that the following formula is satisfied: Rp0.2target=416.53+113.26·log Q+4.0479·R+2694.9·C %?82.750·(log Q)2?0.04279·R2?2.2601·log Q·R+16.9·Cr %+26.1·Mo %+83.6·N %+Z??(1) wherein Rp0.2target is targeted yield strength and is 800-1100 MPa and 0<Q<3.6.

Abstract: A high-strength steel having a minimum yield strength of 1300 MPa may include 0.23% to 0.25% by weight carbon, 0.15% to 0.35% by weight silicon, 0.85% to 1.00% by weight manganese, 0.07% to 0.10% by weight aluminium, 0.65% to 0.75% by weight chromium, 0.02% to 0.03% by weight niobium, 0.55% to 0.65% by weight molybdenum, 0.035% to 0.05% by weight vanadium, 1.10% to 1.30% by weight nickel, 0.0020% to 0.0035% by weight boron, and 0.0007% to 0.0030% by weight calcium. The high-strength steel may also include iron, unavoidable impurities, and at least one of the following: at most 0.012% by weight phosphorus, at most 0.003% by weight sulfur, at most 0.10% by weight copper, at most 0.006% by weight nitrogen, at most 0.008% by weight titanium, at most 0.03% by weight tin, at most 2.00 ppm hydrogen, at most 0.01% by weight arsenic, or at most 0.01% by weight cobalt. A method for producing such high-strength steel is also disclosed.

Abstract: The invention relates to a method for producing a high-strength ferritic austenitic duplex stainless steel with the TRIP (Transformation induced plasticity) effect with deformation. After the heat treatment on the temperature range of 950-1150° C. in order to have high tensile strength level of at least 1000 MPa with retained formability the ferritic austenitic duplex stainless steel is deformed with a reduction degree of at least 10%, preferably at least 20% so that with a reduction degree of 20% the elongation (A50) is at least 15%.

Abstract: A filament according to an aspect of the present invention includes a predetermined chemical composition, in which a diameter r of the filament is 0.15 mm to 0.35 mm, a soft portion is formed along an outer circumference of the filament, the Vickers hardness of the soft portion is lower than that of a position of the filament at a depth of ¼ of the diameter r by Hv 50 or higher, the thickness of the soft portion is 1 ?m to 0.1×r mm, the metallographic structure of a center portion of the filament contains 95% to 100% of pearlite by area %, the average lamellar spacing of pearlite in a portion from a surface of the filament to a depth of 1 ?m is less than that of pearlite at the center of the filament, the difference between the average lamellar spacing of pearlite in the portion from the surface of the filament to the depth of 1 ?m and the average lamellar spacing of pearlite at the center of the filament is 2.0 nm or less, and the tensile strength is 3200 MPa or higher.

Abstract: A high strength hot rolled steel sheet is provided with low yield ratio and that is excellent in low-temperature toughness. The hot rolled steel sheet can be used as a raw material of a steel pipe. The steel sheet has a chemical composition containing C: 0.03% or more and 0.10% or less, Si: 0.01% or more and 0.50% or less, Mn: 1.4% or more and 2.2% or less, P: 0.025% or less, S: 0.005% or less, Al: 0.005% or more and 0.10% or less, Nb: 0.02% or more and 0.10% or less, Ti: 0.001% or more and 0.030% or less, Mo: 0.01% or more and 0.50% or less, Cr: 0.01% or more and 0.50% or less, and Ni: 0.01% or more and 0.50% or less, in which the condition that Moeq is 1.4% or more and 2.2% or less.

Abstract: Provided are a steel plate having high tensile strength, high yield strength, and excellent low-temperature toughness and a method for manufacturing the steel plate. A steel plate contains 0.04% to 0.15% C, 0.1% to 2.0% Si, 0.8% to 2.0% Mn, 0.025% or less P, 0.020% or less S, 0.001% to 0.100% Al, 0.010% to 0.050% Nb, and 0.005% to 0.050% Ti and further contains Cu, Ni, Cr, Mo, and N on a mass basis such that 0.5%?Cu+Ni+Cr+Mo?3.0% and 1.8?Ti/N?4.5 are satisfied, the remainder being Fe and inevitable impurities. The area fraction of polygonal ferrite is less than 10%. The effective grain size at the through-thickness center is 15 ?m or less. The standard deviation of the effective grain size is 10 ?m or less.

Abstract: A method for press-hardening steel in which a steel sheet composed of a hardenable steel alloy can either be preformed in a cold state, then transferred to a tool that has the contour of the preformed component and in it, after a preceding heating step that produces a complete austenitization, is cooled in this tool at a speed greater than the critical hardening speed so that a quench hardening of the preformed component is achieved, or a sheet blank composed of a steel with a composition that permits a press hardening is heated to a temperature above the austenitization temperature and is then hot-formed and at the same time, cooled at a speed that is greater than the critical hardening speed so that hardening is produced; and the hardening is produced in that the austenitic structure is converted into an essentially martensitic structure, possibly with a residual quantity of austenite.

Abstract: A multi-phase hot-rolled steel sheet has a metallurgical structure having a main phase of ferrite with an average grain diameter of at most 3.0 ?m and a second phase including at least one of martensite, bainite, and austenite. In the surface layer, the average grain diameter of the second phase is at most 2.0 ?m, the difference (?nHav) between the average nanohardness of the main phase (nH?av) and the average nanohardness of the second phase (nH2nd av) is 6.0-10.0 GPa, the difference (??nH) of the standard deviation of the nanohardness of the second phase from the standard deviation of the nanohardness of the main phase is at most 1.5 GPa, and in the central portion, the difference (?nHav) between the average nanohardnesses is at least 3.5 GPa to at most 6.0 GPa and the difference (??nH) between the standard deviations of the nanohardnesses is at least 1.5 GPa.

Abstract: A thick-walled high-strength hot rolled steel sheet having excellent hydrogen induced cracking resistance which is preferably used as a raw material for a high-strength welded steel pipe of X65 grade or more and a method of manufacturing the thick-walled high-strength hot rolled steel sheet are provided. The composition of the thick-walled high-strength hot rolled steel sheet contains by mass % 0.02 to 0.08% C, 0.50 to 1.85% Mn, 0.02 to 0.10% Nb, 0.001 to 0.05% Ti, 0.0005% or less B in such a manner that (Ti+Nb/2)/C<4 is satisfied or also contains one or two kinds or more of 0.010% or less Ca, 0.02% or less REM, and Fe and unavoidable impurities as a balance. The steel sheet has the structure formed of a bainitic ferrite phase or a bainite phase. Surface layer hardness is 230HV or less in terms of Vickers hardness.

Abstract: A hollow seamless pipe for a high-strength spring with reduced occurrence of decarburization in the inner and outer peripheral surfaces, hardened surface layers in the inner and outer peripheral surfaces during quenching, and sufficient fatigue strength is provided. The hollow seamless pipe contains a steel material, which includes 0.2 to 0.7 mass % of C, 0.5 to 3 mass % of Si, 0.1 to 2 mass % of Mn, more than 0 and 0.1 mass % or less of Al, more than 0 and 0.02 mass % or less of P, more than 0 and 0.02 mass % or less of S, and more than 0 and 0.02 mass % or less of N. The C content in the inner and outer peripheral surfaces is 0.10 mass % or more. A thickness of a whole decarburized layer in each of the inner peripheral surface and the outer peripheral surface is 200 ?m or less.

Abstract: A steel, namely for marine applications, comprises by weight percent: carbon: 0.05 to 0.20; silicon: 0.15 to 0.55; manganese: 0.60 to 1.60; chromium: 0.75 to 1.50; aluminum: 0.40 to 0.80; niobium and/or vanadium: 0.01<[Nb]+[V]<0.60; sulphur: up to 0.045; and phosphorous: up to 0.045.

Abstract: A cold-rolled steel sheet having a refined structure in which grain growth during annealing is suppressed has a chemical composition containing, in mass percent, controlled amounts of carbon, manganese, niobium, titanium, vanadium, sol. Aluminum, chromium, molybdenum, boron, calcium, and REM and a microstructure which contains at least 50% by area of ferrite as a main phase, a second phase containing at least 10% by area of a low temperature transformation phase and 0-3% by area of retained austenite and which satisfies the following Equations (1)-(3), in addition to a particular texture, dm<2.7+10000/(5+300×C+50×Mn+4000×Nb+2000×Ti+400×V)2??(1), dm<4.0??(2), and ds?1.5??(3), wherein dm is the average grain diameter (?m) of ferrite defined by a high angle grain boundary having a tilt angle of at least 15°, and ds is the average grain diameter (?m) of the second phase.

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

Abstract: A steel material has a chemical composition containing, by mass %, C: 0.005% or more and 0.06% or less, Si: 0.05% or more and 0.5% or less, Mn: 0.2% or more and 1.8% or less, Cr: 15.5% or more and 18.0% or less, Ni: 1.5% or more and 5.0% or less, V: 0.02% or more and 0.2% or less, Al: 0.002% or more and 0.05% or less, N: 0.01% or more and 0.15% or less, O: 0.006% or less, and further contains one or more of Mo: 1.0% or more and 3.5% or less, W: 3.0% or less and Cu: 3.5% or less, in which Cr+0.65Ni+0.60Mo+0.30W+0.55Cu-20C?19.5 and Cr+Mo+0.50W+0.30Si-43.5C-0.4Mn—Ni-0.3Cu-9N?11.5 are satisfied, is made into a seamless steel tube by performing heating and hot rolling.

Abstract: When the amount of C, the amount of Si and the amount of Mn are respectively represented by [C], [Si] and [Mn] in unit mass %, the cold rolled steel sheet satisfies a relationship of (5×[Si]+[Mn])/[C]>10, the metallographic structure contains, by area ratio, 40% to 90% of a ferrite and 10% to 60% of a martensite, further contains one or more of 10% or less of a pearlite by area ratio, 5% or less of a retained austenite by volume ratio and 20% or less of a bainite by area ratio, the hardness of the martensite measured using a nanoindenter satisfies H20/H10<1.10 and ?HM0<20, and TS×? representing the product of TS that is a tensile strength and ? that is a hole expansion ratio is 50000 MPa·% or more.

Abstract: A cold rolled steel sheet according to the present invention satisfies an expression of (5×[Si]+[Mn])/[C]>11 when [C] represents an amount of C by mass %, [Si] represents an amount of Si by mass %, and [Mn] represents an amount of Mn by mass %, a metallographic structure before hot stamping includes 40% to 90% of a ferrite and 10% to 60% of a martensite in an area fraction, a total of an area fraction of the ferrite and an area fraction of the martensite is 60% or more, a hardness of the martensite measured with a nanoindenter satisfies an H2/H1<1.10 and ?HM<20 before the hot stamping, and TS×? which is a product of a tensile strength TS and a hole expansion ratio ? is 50000 MPa·% or more.

Abstract: A low yield ratio and high-strength hot rolled steel sheet having a composition containing, on a mass percent basis, 0.03% to 0.10% C, 0.10% to 0.50% Si, 1.4% to 2.2% Mn, 0.005 % to 0.10% Al, 0.02% to 0.10% Nb, 0.001% to 0.030% Ti, 0.05% to 0.50% Mo, 0.05% to 0.50% Cr, and 0.01% to 0.50% Ni, in which Moeq preferably satisfies the range of 1.4% to 2.2%; and a microstructure including a main phase that contains bainitic ferrite having an average grain size of 10 ?m or less and a secondary phase that contains massive martensite having an aspect ratio of less than 5.0 in an area ratio of 1.4% to 15%.

Abstract: An austenitic heat resistant alloy, which comprises by mass percent, C: over 0.02 to 0.15%, Si?2%, Mn?3%, P?0.03%, S?0.01%, Cr: 28 to 38%, Ni: over 40 to 60%, Co?20% (including 0%), W over 3 to 15%, Ti: 0.05 to 1.0%, Zr: 0.005 to 0.2%, Al: 0.01 to 0.3%, N?0.02%, and Mo<0.5%, with the balance being Fe and impurities, in which the following formulas (1) to (3) are satisfied has high creep rupture strength and high toughness after a long period of use at a high temperature, and further it is excellent in hot workability. This austenitic heat resistant alloy may contain a specific amount of one or more elements selected from Nb, V, Hf, B, Mg, Ca, Y, La, Ce, Nd, Sc, Ta, Re, Ir, Pd, Pt and Ag. P?3/{200(Ti+8.5×Zr)} . . . (1), 1.35×Cr?Ni+Co?1.85×Cr . . . (2), Al?1.5×Zr . . . (3).

Abstract: The present invention provides a high-strength wear-resistant steel plate with Brinell hardness of ?HB420, comprising the following chemical compositions (by weight %) C: 0.205-0.25%, Si: 0.20-1.00%, Mn: 1.0-1.5%, P?0.015%, S?0.010%, Al: 0.02-0.04%, Ti: 0.01-0.03%, N?0.006%, Ca?0.005%, and more than one of Cr?0.70%, Ni?0.50%, Mo?0.30%, other compositions being Ferrum and unavoidable impurities. Also provided is a method of manufacturing the wear-resistant steel plate has remarkable TRIP effect in use, improving substantially its wear resistance, thereby meeting the high demand for wear-resistant steel plates in related industries.

Abstract: A seamless steel pipe for line pipe having high strength and high toughness contains, by mass percent, C: 0.02 to 0.10%, Si: at most 0.5%, Mn: 0.5 to 2.0%, Al: 0.01 to 0.1%, P: at most 0.03%, S: at most 0.005%, Ca: at most 0.005%, and N: at most 0.007%, and further contains at least one selected from a group consisting of Ti: at most 0.008%, V: less than 0.06%, and Nb: at most 0.05%, the balance being Fe and impurities. A carbon equivalent Ceq defined by Formula (1) is at least 0.38, a content of Ti, V and Nb satisfies Formula (2), and the size of carbo-nitride containing at least one of Ti, V, Nb and Al is at most 200 nm, Ceq=C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15??(1) Ti+V+Nb<0.06??(2).

Abstract: Disclosed is high strength spring steel that can limit the depth of pitting occurring when corroded and therefore possesses high strength as well as excellent pitting corrosion resistance and corrosion fatigue property, with a composition containing: C: greater than 0.35 mass % and less than 0.50 mass %; Si: greater than 1.75 mass % and less than or equal to 3.00 mass %; Mn: 0.2 mass % to 1.0 mass %; Cr: 0.01 mass % to 0.04 mass %; P: 0.025 mass % or less; S: 0.025 mass % or less; Mo: 0.1 mass % to 1.0 mass %; and O: 0.0015 mass % or less, under a condition that a PC value calculated by PC=4.2×([C]+[Mn])+0.1×(1/[Si]+1/[Mo])+20.3×[Cr]+0.001×(1/[N]) is greater than 3.3 and equal to or less than 8.0. Also disclosed is a preferred method for manufacturing the same.

Abstract: An austenitic heat resistant alloy, which comprises by mass percent, C: over 0.02 to 0.15%, Si?2%, Mn?3%, P?0.03%, S?0.01%, Cr: 28 to 38%, Ni: over 40 to 60%, Co?20% (including 0%), W over 3 to 15%, Ti: 0.05 to 1.0%, Zr: 0.005 to 0.2%, Al: 0.01 to 0.3%, N?0.02%, and Mo<0.5%, with the balance being Fe and impurities, in which the following formulas (1) to (3) are satisfied has high creep rupture strength and high toughness after a long period of use at a high temperature, and further it is excellent in hot workability. This austenitic heat resistant alloy may contain a specific amount of one or more elements selected from Nb, V, Hf, B, Mg, Ca, Y, La, Ce, Nd, Sc, Ta, Re, Ir, Pd, Pt and Ag. P?3/{200(Ti+8.5×Zr)}??(1), 1.35×Cr?Ni+Co?1.85×Cr??(2), Al?1.5×Zr??(3).

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: A method of fabricating a martensitic stainless steel including: 1) heating steel to a temperature higher than austenizing temperature of the steel, then quenching the steel until a hottest portion of the steel is at a temperature less than or equal to a maximum temperature, and greater than or equal to a minimum temperature, a cooling rate being sufficiently fast for austenite not to transform into a ferrito-perlitic structure; 2) performing a first anneal followed by cooling until the hottest portion of the steel is at a temperature less than or equal to the maximum temperature and greater than or equal to the minimum temperature; 3) performing a second anneal followed by cooling to ambient temperature; and at the end of each of 1) and 2), performing: ?) as soon as temperature of the hottest portion of the steel reaches the maximum temperature, immediately heating the steel once more.

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

Abstract: A high carbon steel sheet having superior strength and ductility and a method for manufacturing the same comprising: 0.2 to 1.0 wt % carbon (C), 0 to 3.0 wt % silicon (Si), 0 to 3.0 wt % manganese (Mn), 0 to 3.0 wt % chromium (Cr), 0 to 3.0 wt % nickel (Ni), 0 to 0.5 wt % molybdenum (Mo), 0 to 3.0 wt % aluminum (Al), 0 to 0.01 wt % boron (B), 0 to 0.5 wt % titanium (Ti), and the remainder substantially being iron (Fe) and inevitable impurities. The contents of carbon, manganese, chromium, and nickel satisfy the following Equation 1, and the contents of silicon and aluminum satisfy the following Equation 2: (3.0?2.5×C)wt %?(Mn+Cr+Ni/2)?8.5 wt %—(Equation 1) Si+Al>1.0 wt % (Equation 2).

Abstract: A structural stainless steel sheet which can be manufactured at a low cost and with high efficiency, and possesses excellent welded-part corrosion resistance and a manufacturing method thereof are provided. The structural stainless steel sheet has a composition which contains by mass % 0.01 to 0.03% C, 0.01 to 0.03% N, 0.10 to 0.40% Si, 1.5 to 2.5% Mn, 0.04% or less P, 0.02% or less S, 0.05 to 0.15% Al, 10 to 13% Cr, 0.5 to 1.0% Ni, 4×(C+N) or more and 0.3% or less Ti, and Fe and unavoidable impurities as a balance, V, Ca and O in the unavoidable impurities being regulated to 0.05% or less V, 0.0030% or less Ca and 0.0080% or less O, wherein an F value expressed by Cr+2×Si+4×Ti?2×Ni?Mn?30×(C+N) satisfies a condition that F value?11 and an FFV value expressed by Cr+3×Si+16×Ti+Mo+2×Al?2×Mn?4×(Ni+Cu)?40×(C+N)+20×V satisfies a condition that FFV value?9.0.

Abstract: The steel wire material for a spring of the invention contains; C: 0.37-0.54%, Si: 1.7-2.30%, Mn: 0.1-1.30%, Cr: 0.15-1.1%, Cu: 0.15-0.6%, Ti: 0.010-0.1%, Al: 0.003-0.05%, and the balance including iron with inevitable impurities, wherein ferrite decarburized layer depth is 0.01 mm or less, whole decarburized layer depth is 0.20 mm or less, and fracture reduction of area is 25% or more. It alternately may contain; C: 0.38-0.47%, Si: 1.9-2.5%, Mn: 0.6-1.3%, Ti: 0.05-0.15%, Al: 0.003-0.1%, and the balance including iron with inevitable impurities, wherein ferrite decarburized layer depth is 0.01 mm or less.

Abstract: A seamless steel pipe for line pipe having high strength and high toughness contains, by mass percent, C: 0.02 to 0.10%, Si: at most 0.5%, Mn: 0.5 to 2.0%, Al: 0.01 to 0.1%, P: at most 0.03%, S: at most 0.005%, Ca: at most 0.005%, and N: at most 0.007%, and further contains at least one selected from a group consisting of Ti: at most 0.008%, V: less than 0.06%, and Nb: at most 0.05%, the balance being Fe and impurities. A carbon equivalent Ceq defined by Formula (1) is at least 0.38, a content of Ti, V and Nb satisfies Formula (2), and the size of carbo-nitride containing at least one of Ti, V, Nb and Al is at most 200 nm, Ceq=C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15??(1) Ti+V+Nb<0.06??(2).

Abstract: A steel material for a solid stabilizer which has high bendability, high hardenability, and high quenching crack resistance, a solid stabilizer having high strength, and a manufacturing method of the solid stabilizer. The steel material for the solid stabilizer contains, in mass %, 0.24 to 0.40% of C, 0.15 to 0.40% of Si, 0.50 to 1.20% of Mn, 0.03% or less of P, 0.30% or less of Cr, 0.01 to 0.03% of Ti, and 0.0010 to 0.0030% of B. The steel material for the solid stabilizer satisfies a condition of formula (1) below. Hardness in a radial center portion of the steel material for the solid stabilizer after tempering is 400 HV or more, and a martensite ratio in the radial center portion after the tempering is 80% or more. 1.24<(2C+0.1Si+0.4Mn+0.4Cr)×{1+(1.5B?300B2)×240}<1.

Abstract: Regarding contents of C, Si, Mn and Cr, a value of parameter P represented by the following (equation 1) is 1000 or more. A metallic structure contains wire-drawn pearlite in an area ratio of 98% or more, a diameter is 0.05 mm to 0.18 mm, a tensile strength is 4000 MPa or more, and a twist number in a twist test in which a grip-to-grip distance is 100 mm, and a tension equal to a tensile strength×a cross-sectional area of wire×0.5 is applied, is 5 or more. P=1098×[C]+98×[Si]?20×[Mn]+167×[Cr]??(equation 1) (in the (equation 1), [C], [Si], [Mn] and [Cr] indicate contents (mass %) of C, Si, Mn and Cr, respectively.

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: The present disclosure relates to a ferritic stainless steel and fabrication method of a ferritic stainless steel comprising, by weight %, C: above 0 wt % to 0.01 wt % or less, Si: above 0 wt % to 0.5 wt % or less, Mn: above 0 wt % to 2.0 wt % or less, P: 0 wt % or more to 0.04 wt % or less, S: 0 wt % or more to 0.02 wt % or less, Cr: 12 wt % or more to 19 wt % or less, Mo: 0 wt % or more to 1.0 wt % or less, W: 2 wt % of more to 7 wt % or less, Ti: 0 wt % or more to 0.3 wt % or less, Nb: above 0 wt % to 0.6 wt % or less, N: above 0 wt % to 0.01 wt % or less, Al: 0 wt % or more to 0.1 wt % or less; and the balance of Fe and other inevitable impurities.

Abstract: An austenitic stainless steel hot-rolled steel material can be provided which has seawater resistance and strength superior to conventional steel. Low-temperature toughness can be maintained, which is preferable in a structural member of speedy craft. The steel material can include an austenitic stainless steel hot-rolled steel material which excels in the properties of corrosion resistance, proof stress, and low-temperature toughness. In such austenitic stainless steel hot-rolling steel material, e.g., PI [=Cr+3.3(Mo+0.5W)+16N] ranges from 35 to 40, ? cal [=2.9 (Cr+0.3Si +Mo+0.5W)?2.6 (Ni+0.3Mn+0.25Cu+35C+20N)?18] ranges from ?6 to +2, and a 0.2% proof stress at room temperature is not less than 550 MPa, Charpy impact value measured using a V-notch test piece at ?40° C. is not less than 100 J/cm2, and the pitting potential measured in a deaerated aqueous solution of 10% NaCl at 50° C. (Vc'100) is not less than 500 mV (as it relates to saturated Ag/AgCl).

Abstract: A method of designing low cost, high strength, high toughness martensitic steel uses mathematical modeling to define optimum low cost chemical compositions, the content of retained austenite, and critical temperatures; melting an ingot, processing same, making steel articles, and heat treating the articles using the critical temperatures and the content of retained austenite. The new steel comprises, by weight, about 0.3-0.45% of C; at most 2.5% of Cr; at most 1.0% of Mo; at most 3.50% of Ni; about 0.3 to 1.5% of Mn; about 0.1-1.3% of Si; about 0.1-1.0% of Cu; Cu being less than Si; about 0.1 to 1.0% of V+Ti+Nb; at most 0.25% of Al; the sum of alloying elements being less than about 11.5%; the balance being essentially Fe and incidental impurities. Procedures of melting, processing and heat treatment using the mathematical model are disclosed.

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: A thick-walled high-strength hot rolled steel sheet having excellent hydrogen induced cracking resistance which is preferably used as a raw material for a high-strength welded steel pipe of X65 grade or more and a method of manufacturing the thick-walled high-strength hot rolled steel sheet are provided. The composition of the thick-walled high-strength hot rolled steel sheet contains by mass % 0.02 to 0.08% C, 0.50 to 1.85% Mn, 0.03 to 0.10% Nb, 0.001 to 0.05% Ti, 0.0005% or less B in such a manner that (Ti+Nb/2)/C<4 is satisfied or also contains one or two kinds or more of 0.010% or less Ca, 0.02% or less REM, and Fe and unavoidable impurities as a balance. The steel sheet has the structure formed of a bainitic ferrite phase or a bainite phase. Surface layer hardness is 230HV or less in terms of Vickers hardness.

Abstract: The steel wire material for a spring of the invention contains; C: 0.37-0.54%, Si: 1.7-2.30%, Mn: 0.1-1.30%, Cr: 0.15-1.1%, Cu: 0.15-0.6%, Ti: 0.010-0.1%, Al: 0.003-0.05%, and the balance including iron with inevitable impurities, wherein ferrite decarburized layer depth is 0.01 mm or less, whole decarburized layer depth is 0.20 mm or less, and fracture reduction of area is 25% or more. It alternately may contain; C: 0.38-0.47%, Si: 1.9-2.5%, Mn: 0.6-1.3%, Ti: 0.05-0.15%, Al: 0.003-0.1%, and the balance including iron with inevitable impurities, wherein ferrite decarburized layer depth is 0.01 mm or less, Ceq1 in the equation (1) below is 0.580 or more, Ceq2 in the equation (2) below is 0.49 or less, and Ceq3 in the equation (3) below is 0.570 or less. Ceq1=[C]+0.11[Si]?0.07[Mn]?0.05[Ni]+0.02[Cr]??(1) Ceq2=[C]+0.30[Cr]?0.15[Ni]?0.70[Cu]??(2) Ceq3=[C]?0.04[Si]+0.24[Mn]+0.10[Ni]+0.20[Cr]?0.89[Ti]?1.92[Nb]??(3) (In the above equations, [ ] shows the content (mass %) of each element in steel.

Abstract: A high-strength seamless steel pipe for oil wells excellent in sulfide stress cracking resistance which comprises, on the percent by mass basis, C: 0.1 to 0.20%, Si: 0.05 to 1.0%, Mn: 0.05 to 1.0%, Cr: 0.05 to 1.5%, Mo: 0.05 to 1.0%, Al: 0.10% or less, Ti: 0.002 to 0.05% and B: 0.0003 to 0.005%, with a value of equation “C+(Mn/6)+(Cr/5)+(Mo/3)” of 0.43 or more, with the balance being Fe and impurities, and in the impurities P: 0.025% or less, S: 0.010% or less and N: 0.007% or less. The seamless steel pipe may contain a specified amount of one or more element(s) of V and Nb, and/or a specified amount of one or more element(s) of Ca, Mg and REM. The seamless steel pipe can be produced at a low cost by adapting an in-line tube making and heat treatment process having a high production efficiency since a reheating treatment for refinement of grains is not required.

Abstract: [Problem to be Solved] A method for producing a duplex stainless steel pipe that has not only a corrosion resistance required for the oil well pipes used in deep oil wells or in severe corrosive environments but also a targeted strength is provided. [Solution] A method for producing a duplex stainless steel pipe having a minimum yield strength of 758.3 to 965.2 MPa, comprising: preparing a duplex stainless steel material pipe for cold working, 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.

Abstract: In a method of manufacturing a high tensile strength thick steel plate, a steel slab contains 0.03-0.055% of C, 3.0-3.5% of Mn, and 0.002-0.10% of Al, the amount of Mo is limited to 0.03% or less, the amount of Si is limited to 0.09% or less, the amount of V is limited to 0.01% or less, the amount of Ti is limited to 0.003% or less, the amount of B is limited to 0.0003% or less, and of which Pcm value representing a weld cracking parameter is fallen within the range of 0.20-0.24% and DI value representing a hardenability index is fallen within the range of 1.00-2.60, is heated to 950-1100° C. The steel slab is subjected to a rolling process with a cumulative draft of 70-90% when a temperature is in a range of 850° C. or more, and then, the steel slab is subjected to a rolling process at 780° C. or higher with a cumulative draft of 10-40% when a temperature is in a range of 780-830° C., and subsequently, accelerated cooling at a cooling rate of 8-80° C./sec is started from 700° C.

Abstract: A steel sheet excellent in mechanical strength, workability and thermal stability and suited for use as a raw material in such fields of manufacturing automobiles, household electric appliances and machine structures and of constructing buildings, and a manufacturing method thereof are provided. The steel sheet is a hot-rolled steel sheet of carbon steel or low-alloy steel, the main phase of which is ferrite, and is characterized in that the average ferrite crystal grain diameter D (?m) at the depth of ¼ of the sheet thickness from the steel sheet surface satisfies the relations respectively defined by the formulas (1) and (2) given below and the increase rate X (?m/min) in average ferrite crystal grain diameter at 700° C. at the depth of ¼ of the sheet thickness from the steel sheet surface and said average crystal grain diameter D (?m) satisfy the relation defined by the formula (3) given below: 1.2?D?7??formula (1) D?2.7+5000/(5+350·C+40·Mn)2??formula (2) D·X?0.

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

Abstract: The occurrence of delayed fracture which is found in a hot worked martensitic stainless steel is prevented by subjecting the steel, after hot working and prior to heat treatment for hardening by quenching from a temperature of at least Ac1 point of the steel, to preliminary softening heat treatment under such conditions that the softening parameter P defined below is at least 15,400 and the softening temperature T is lower than the Ac1 point: P(softening parameter):P=T(20+log t) T: softening temperature [K] t: duration of softening treatment [Hr]. The present invention is particularly effective for a martensitic stainless steel having a steel composition in which the amount of effective dissolved C and N (=[C*+10N*]) where C* and N* are calculated by the following formulas is larger than 0.45: C*=C?[12{(Cr/52)×(6/23)}/10, and N*=N?[14{(V/51)+(Nb/93)}/10]?[14{(Ti/48)+(B/11)+(Al/27)}/10].