Abstract: A high strength, high toughness steel alloy is disclosed. The alloy has the following broad weight percent composition. Element Broad C 0.35-0.55 Mn 0.6-1.2 Si 0.9-2.5 P 0.01 max. S 0.001 max.? Cr 0.75-2.0? Ni 3.5-7.0 Mo + ½ W 0.4-1.3 Cu 0.5-0.6 Co 0.01 max. V + ( 5/9) × Nb 0.2-1.0 Fe Balance Included in the balance are the usual impurities found in commercial grades of steel alloys produced for similar use and properties. Also disclosed is a hardened and tempered article that has very high strength and fracture toughness. The article is formed from the alloy having the broad weight percent composition set forth above. The alloy article according to this aspect of the invention is further characterized by being tempered at a temperature of about 500° F. to 600° F.

Abstract: A steel product for a line pipe according to the invention has a composition containing, in mass %, C : 0.03% to 0.15%, Si: 0.05% to 1.0%, Mn: 0.5% to 1.8%, P: 0.015% or less, S: 0.004% or less, O: 0.01% or less, N: 0.007% or less, sol. Al: 0.01% to 0.1%, Ti: 0.024% or less, Ca: 0.0003% to 0.02%, and the balance consisting of Fe and impurities. The size of TiN in the steel product for a line pipe is at most 30 ?m. The steel product has high HIC resistance and its crack area ratio can be reduced to 3% or less.

Abstract: The present invention provides: a steel for a welded structure to be used for a crude oil tank that exhibits excellent general and local corrosion resistance in crude oil corrosion caused in a steel oil tank and is capable of suppressing the formation of corrosion products (sludge) containing solid sulfur; a method for producing said steel; a crude oil tank; and a method for preventing a crude oil tank against corrosion. The present invention makes it possible to obtain general and local corrosion resistance in a crude oil tank environment and suppress the formation of corrosion products (sludge) containing solid sulfur by using a steel: containing, in mass, 0.001 to 0.2% C, 0.01 to 2.5% Si, 0.1 to 2% Mn, 0.03% or less P, 0.007% or less S, 0.01 to 1.5% Cu, 0.001 to 0.3% Al, 0.001 to 0.01% N as basic components and, further, 0.01 to 0.2% Mo and/or 0.01 to 0.5% W; and preferably satisfying the following expression; Solute Mo+Solute W?0.005%.

Abstract: A low alloy steel, which has a chemical composition by mass %, of C: 0.1 to 0.55%, Si: 0.05 to 0.5%, Mn: 0.1 to 1%, S: 0.0001 to 0.005%, Al: 0.005 to 0.08%, Ti: 0.005 to 0.05%, Cr: 0.1 to 1.5%, Mo: 0.1 to 1%, O: 0.0004 to 0.005%, Ca: 0.0005 to 0.0045%, Nb: 0 to 0.1%, V: 0 to 0.5%, B: 0 to 0.005%, Zr: 0 to 0.10%, P?0.03%, and N?0.006%, with the balance being Fe and impurities, is manufactured by adjusting the value of ([Ti]/47.9)([N]/14)/([Ca])/40.1) satisfies not less than 0.0008 and not more than 0.0066, at the time of melting the said low alloy steel, wherein [Ti], [N] and [Ca] are the contents in the molten steel by mass % of Ti, N and Ca respectively. The thus-manufactured low steel alloy has a high SSC resistance with a yield stress of not less than 758 MPa.

Abstract: Provided is a hot-working steel excellent in machinability and impact value comprising, in mass %, C: 0.06 to 0.85%, Si: 0.01 to 1.5%, Mn: 0.05 to 2.0%, P: 0.005 to 0.2%, S: 0.001 to 0.35%, and Al: 0.06 to 1.0% and N: 0.016% or less, in contents satisfying Al×N×105?96, and a balance of Fe and unavoidable impurities, total volume of AlN precipitates of a circle-equivalent diameter exceeding 200 nm accounting for 20% or less of total volume of all AlN precipitates.

Abstract: A steel for nitrocarburizing use, which comprises by mass percent, C: more than 0.45% to not more than 0.60%, Si<0.50%, Mn: more than 1.30% to not more than 1.70%, P?0.05%, S: 0.02 to 0.10%, Cr?0.30% and N: more than 0.007% to not more than 0.030%, and which further contains one or two elements selected from Al: more than 0.010% to not more than 0.10% and Ti: more than 0.005% to not more than 0.035%, with Al+Ti being 0.015% or more, with the balance being Fe and impurities, wherein V among the impurities is not more than 0.010%, and further satisfies the following 2 formulas, has high fatigue strength and excellent straightenability after the nitrocarburizing treatment, without performing the expensive heat treatment of quenching and tempering. Consequently, they are suitable as raw materials for nitrocarburized components: fn1=1.25C+Mn?0.1Cr, fn2=N?0.45Al?( 1/22)Ti.

Abstract: Provided is a low alloy steel for high-pressure hydrogen gas environments, which contains, by mass percent, C: 0.15 to 0.60%, Si: 0.05 to 0.5%, Mn: 0.05 to 3.0%, P: not more than 0.025%, S: not more than 0.010%, Al: 0.005 to 0.10%, Mo: 0.5 to 3.0%, V: 0.05 to 0.30%, O (oxygen): not more than 0.01%, N: not more than 0.03%, and the balance Fe and impurities, and has tensile strength of not less than 900 MPa. This low alloy steel desirably contains B of 0.0003 to 0.003%, but in this case, N is limited to not more than 0.010%. It is desirable to contain at least one among Cr, Nb, Ti, Zr, and Ca. The contents of Mo and V desirably satisfy the following formula (1): [Mo(%)]·[V(%)]0.2?0.32??(1).

Abstract: The present invention provides a steel material for automobile chassis parts which has high fatigue characteristics, does not require much cost for heat treatment, and further is superior in shapeability and a method of production of automobile chassis parts using this steel material, that is, one being a steel material to which Nb and Mo have been compositely added and having a difference 50 to 150 points between a Vicker's hardness of the center of plate thickness and a maximum value of Vicker's hardness within 0.5 mm from the surface after bending by a bending R of the plate outer surface of 2 to 5 times the plate thickness. The surface is high in hardness and the center part is low in hardness, so the fatigue characteristics and shapeability are superior. Note that if annealing under conditions giving a tempering parameter ? defined by ?=T(20+log(t)) of 14000 to 19000 (where T is the absolute temperature, t is the time (h), and the temperature rise is 660° C.

Abstract: A high strength steel sheet with both excellent elongation and stretch-flanging performance is provided. The high strength steel sheet of the present invention comprises, in percent by mass, C: 0.05 to 0.3%, Si: 0.01 to 3.0%, Mn: 0.5 to 3.0%, Al: 0.01 to 0.1%, and Fe and inevitable impurities as the remainder, and has a structure mainly composed of tempered martensite and annealed bainite. The space factor of the tempered martensite is 50 to 95%, the space factor of the annealed bainite is 5 to 30%, and the mean grain size of the tempered martensite is 10 ?m or smaller in terms of the equivalent of a circle diameter. The steel sheet has a tensile strength of 590 MPa or higher.

Abstract: The invention provides a high-strength pearlitic steel rail, which is inexpensive, and has a tensile strength of 1200 MPa or more, and is excellent in delayed fracture properties. Specifically, the rail contains, in mass percent, C of 0.6 to 1.0%, Si of 0.1 to 1.5%, Mn of 0.4 to 2.0%, P of 0.035% or less, S of 0.0005 to 0.010%, and the remainder is Fe and inevitable impurities, wherein tensile strength is 1200 MPa or more, and size of a long side of an A type inclusion is 250 mm or less in at least a cross-section in a longitudinal direction of a rail head, and the number of A type inclusions, each having a size of a long side of 1 mm to 250 mm, is less than 25 per observed area of 1 mm2 in the cross-section in the longitudinal direction of the rail head.

Abstract: The invention provides a machine structural steel excellent in machinability and strength properties that has good machinability over a broad range of machining speeds and also has high impact properties and high yield ratio, which machine structural steel comprises, in mass %, C: 0.1 to 0.85%, Si: 0.01 to 1.5%, Mn: 0.05 to 2.0%, P: 0.005 to 0.2%, S: 0.001 to 0.15%, total Al: greater than 0.05% and not greater than 0.3%, Sb: less than 0.0150% (including 0%), and total N: 0.0035 to 0.020%, solute N being limited to 0.0020% or less, and a balance of Fe and unavoidable impurities.

Abstract: Disclosed is a steel sheet, containing: Si: 0.20-2% (the term “%” herein means “mass %”, the same is true hereinbelow), Mn: 1-2.5%, a total mass of Si and Mn being 1.5% or more, and O: 0.002% or less (exclusive of 0%), C: 0.02-0.25%, P: 0.1% or less (exclusive of 0%), S: 0.05% or less (exclusive of 0%), Al—0.02-0.2%, and N: 0.0015-0.015%. The steel sheet of the invention can be advantageously used for forming wide beads even in high-speed arc welding of 100 cm/min or higher.

Abstract: Provided is a weld metal for Cr—Mo steels which is suppressed in the formation of ferrite bands and therefore has heightened toughness and tensile strength and at the same time, good SR cracking resistance. The weld metal according to the present invention contains C: 0.02 to 0.06% (mass %, which will equally apply hereinafter), Si: 0.1 to 1.0%, Mn: 0.3 to 1.5%, Cr: 2.0 to 3.25%, Mo: 0.8 to 1.2%, Ti: 0.010 to 0.05%, B: 0.0005% or less (inclusive of 0%), N: 0.002 to 0.0120%, O: 0.03 to 0.07%, and the balance being Fe and inevitable impurities, wherein a ratio of the Ti content [Ti] to the N content [N] satisfies the following range: 2.00<[Ti]/[N]<6.25.

Abstract: A high-strength steel sheet according to the present invention not only is suitably adjusted in its chemical elements composition, but also has a DE value defined by the following Equation (1) of 0.0340% or more, and a carbon equivalent Ceq defined by the following Equation (2) of 0.45% or less: DE value=[Ti]+[Nb]+0.3[V]+0.0075[Cr]??(1) where, [Ti], [Nb], [V], and [Cr] represent contents (mass %) of Ti, Nb, V, and Cr, respectively; Ceq=[C]+[Mn]/6+([Cr]+[Mo]+[V])/5+([Cu]+[Ni])/15 ??(2) where, [C], [Mn], [Cr], [Mo], [V], [Cu], and [Ni] represent contents (mass %) of C, Mn, Cr, Mo, V, Cu, and Ni, respectively. A high-strength steel sheet resistant to strength reduction and good in low-temperature toughness of HAZ even when subjected for a long time to a stress-relief annealing process after being processed by welding, is provided.

Abstract: The invention relates to an ultrahigh-strength thin steel sheet excellent in the hydrogen embrittlement resistance, the steel sheet including, by weight %, 0.10 to 0.60% of C, 1.0 to 3.0% of Si, 1.0 to 3.5% of Mn, 0.15% or less of P, 0.02% or less of S, 1.5% or less of Al, 0.003 to 2.0% of Cr, and a balance including iron and inevitable impurities; in which grains of residual austenite have an average axis ratio (major axis/minor axis) of 5 or more, the grains of the residual austenite have an average minor axis length of 1 ?m or less, and the grains of the residual austenite have a nearest-neighbor distance between the grains of 1 ?m or less.

Abstract: A high tensile strength hot-rolled steel sheet having superior strain aging hardenability, which has high formability and stable quality characteristics, and in which satisfactory strength is obtained when the steel sheet is formed into automotive components, thus enabling the reduction in weight of automobile bodies. Specifically, a method for producing a high tensile strength hot-rolled steel sheet having superior strain aging hardenability with a BH of 80 MPa or more, a ?TS of 40 MPa or more, and a tensile strength of 440 MPa or more includes the steps of heating a steel slab to 1,000° C. or more, the steel slab containing, in percent by mass, 0.15% or less of C, 0.45% or less of Si, 3.0% or less of Mn, 0.08% or less of P, 0.02% or less of S, 0.02% or less of Al, 0.0050% to 0.0250% of N, and optionally 0.1% or less in total of at least one of more than 0.02% to 0.1% of Nb and more than 0.02% to 0.1% of V, the ratio N (mass %)/Al (mass %) being 0.

Abstract: A main object thereof is to provide a non-oriented electrical steel sheet being excellent in surface characteristics and having both excellent mechanical characteristics and magnetic characteristics necessary for a rotor of rotating machines such as motors and generators which rotate at a high speed, and a method for producing the same. To achieve the object, the present invention provides a non-oriented electrical steel sheet comprising in % by mass: 0.06% or less of C; 3.5% or less of Si; from 0.05% or more to 3.0% or less of Mn; 2.5% or less of Al; 0.30% or less of P; 0.04% or less of S; 0.02% or less of N; at least one element selected from the group consisting of Nb, Ti, Zr and Vin the predetermined range; and a balance consisting of Fe and impurities; and having a recrystallized fraction being less than 90%.

Abstract: Disclosed is a forging steel characterized in that prescribed composition of components must be satisfied. In particular, any one of the below-mentioned (I)-(IV) need be complied with in regard to dissolved Ca and dissolved Mg. (I) Dissolved Ca: 2-500 ppb (meaning “mass ppb” hereafter) and dissolved Mg: 0.04-5 ppm (meaning “mass ppm” hereafter); (II) Dissolved Ca: 2-100 ppb and dissolved Mg: 5-ppm; (III) Dissolved Ca: 2 ppb or less (0% not included) and dissolved Mg: 0.04-5 ppm; (IV) Dissolved Ca: 2-500 ppb and dissolved Mg: 0.04 ppm or less (0% not included).

Abstract: A low-carbon resulfurized free-machining steel is excellent in machinability and contains 0.02% to 0.15% by mass of C; 0.004% by mass or less (exclusive of 0%) of Si; 0.6% to 3% by mass of Mn; 0.02% to 0.2% by mass of P; 0.35% to 1% by mass of S; 0.005% by mass or less (exclusive of 0% by mass) of Al; 0.008% to 0.03% by mass of 0; and 0.007% to 0.03% by mass of N, with the remainder being iron and inevitable impurities, in which the ratio [Mn]/[S] of the manganese content [Mn] to the sulfur content [S] is within the range of 3 to 4, and the carbon content [C], the manganese content [Mn] and the nitrogen content [N] satisfy the following Expression (1): 10[C]×[Mn]?0.94+1226[N]2?1.2, wherein [C], [Mn] and [N] represent the contents on the percent by mass basis of carbon, manganese, and nitrogen, respectively.

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

Abstract: A seamless steel pipe for line pipe having a high strength and good toughness and corrosion resistance even though having a thick wall has a chemical composition comprising, in mass percent, C: 0.02-0.08%, Si: at most 0.5%, Mn: 1.5-3.0%, Al: 0.001-0.10%, Mo: greater than 0.4% to 1.2%, N: 0.002-0.015%, Ca: 0.0002-0.007%, and a remainder of Fe and impurities, wherein the contents of the impurities are at most 0.03% for P, at most 0.005% for S, at most 0.005% for O and less than 0.0005% for B and wherein the value of Pcm calculated by the following Equation (1) is at least 0.185 and at most 0.250. The steel pipe has a microstructure which primarily comprises bainite and which has a length of cementite of at most 20 micrometers: Pcm=[C]+[Si]/30+([Mn]+[Cr]+[Cu])/20+[Mo]/15+[V]/10+5[B]??(1) wherein [C], [Si], [Mn], [Cr], [Cu], [Mo], [V] and [B] are numbers respectively indicating the content in mass percent of C, Si, Mn, Cr, Cu, Mo, V and B.

Abstract: A method of producing coil plate on a hot strip mill is disclosed. The method includes coiling hot rolled coil plate strip at a temperature that is selected (a) to minimise precipitation of Cr/Mo carbides or (b) so that any Cr/Mo carbides that form are sufficiently fine that they go into solution in any subsequent heat treatment of coil plate made from the strip.

Abstract: A low alloy steel is provided for oil country tubular goods with a yield strength between 654 MPa and 757 MPa, and possessing excellent resistance to HIC and SSC in high-pressure hydrogen sulfides environment, and comprising, by mass %: 0.10 to 0.60% C; 0.05 to 0.5% Si; 0.05 to 3.0% Mn; 0.025% or less P; 0.010% or less S; 0.005 to 0.10% Al; 0.01% or less O (oxygen); 3.0% or less Cr; and 3.0% or less Mo, wherein the amount of Cr and Mo content is 1.2% or more, with the balance being Fe and impurities, and the number of nonmetallic inclusions whose major axis is 10 ?m or more is 10 per square millimeter in the inspected cross section. The present invention provides a low alloy steel for oil country tubular goods possessing excellent resistance to sulfide stress cracking, and a seamless steel pipe.

Abstract: The present invention provides high strength thick steel plate superior in crack arrestability high in strength, free of deterioration of HAZ toughness, and free of anisotropy, that steel plate containing, by mass %, C: 0.03 to 0.15%, Si: 0.1 to 0.5%, Mn: 0.5 to 2.0%, P: ?0.02%, S: ?0.01%, Al: 0.001 to 0.1%, Ti: 0.005 to 0.02%, Ni: 0.15 to 2%, and N: 0.001 to 0.008% and having a balance of iron and unavoidable impurities as chemical components, having a microstructure of a ferrite and/or pearlite structure with bainite as a matrix phase, and having an average circle equivalent diameter of crystal grains with a crystal misorientation angle of 15° or more of 15 ?m or less in the regions of 10% of plate thickness from the front and rear surfaces and of 40 ?m or less in the other region including the center part of plate thickness.

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: The present invention provides steel plate for high strength line pipe suppressing the rise in yield strength in the longitudinal direction of expanded steel pipe due to the heating at the time of coating to prevent corrosion and superior in strain aging resistance and steel pipe for the material for the same, that is, high strength steel pipe for line pipe superior in strain aging resistance characterized in that a base material having a composition of chemical elements containing, by mass %, Mo: over 0% to less than 0.15% and Mn: 1.7 to 2.5%, satisfying Mo/Mn: over 0 to 0.08, containing C, Si, P, S, Al, Ti, N, and B, furthermore containing one or more of Ni, Cu, and Cr, having a balance of iron and unavoidable impurities, having a P value of 2.5 to 4.0 in range, and having a metallurgical structure comprised of bainite and martensite: P value=2.7C+0.4Si+Mn+0.8Cr+0.45(Ni+Cu)+2Mo. Furthermore, it may contain one or more of Nb, V, Ca, REM, and Mg.

Abstract: The present invention provides first resistant steel superior in fire resistance having less variation in material quality and exhibiting a yield strength of ? or more of that at ordinary temperature even at 600° C. and a method of production of the same, that is, fire resistant steel characterized by containing, by mass %, C: 0.01 to 0.03%, Mn: 0.2 to 1.7%, Si: 0.5% or less, Cu: 0.7 to 2%, Mo: 0.8% or less, Nb: 0.01 to 0.3%, Ti: 0.005 to 0.03%, N: 0.006% or less, B: 0.0003 to 0.003%, V: 0.2% or less, Cr: 1% or less, Al: 0.1% or less, P: 0.03% or less, and S: 0.02% or less, containing Ni by mass ratio of Ni/Cu of 0.6 to 0.9, and comprising a balance of Fe and unavoidable impurities, and having a yield strength at 600° C. of 60% of the yield strength at 21° C.

Abstract: The present invention provides a rolled material having excellent fracture splitting characteristics and suitable for the manufacture of a connecting rod in which a through-hole section for assembly in a crankshaft is fracture split in substantially semicircles. Prescribed components are contained, an average aspect ratio of a sulfide-based inclusion as observed in a D/4 portion (D is the diameter of the rolled material) in a cross-section parallel to a longitudinal direction of the rod-shaped rolled material is not more than 10.0, a Pc indicated in Equation (1) below is between 0.41 and 0.75, and a Veq indicated in Equation (2) below is not less than 0.18 mass % Pc=C(1??/100)??(1) {In Equation (1), C represents the carbon content in steel (mass %) and ? represents the ferrite fraction (area ratio %)} Veq=V+Ti/2+Si/20??(2) {In Equation (2), V, Ti and Si represent the content of each element in steel (mass %)}.

Abstract: A steel plate for submerged arc welding having good low temperature toughness at a fusion line vicinity part and a boundary with the base material in HAZ as well as at the base material and the weld metal is provided. The steel plate for submerged arc welding according to the invention contains, by mass, 0.03% to 0.09% C, 1.5% to 2.5% Mn, 0.005% to 0.025% Nb, 0.005% to 0.02% Ti, 0.01% to 0.06% Al, at most 0.0005% B, 0.001% to 0.008% N, at most 0.015% P, at most 0.015% S, and at most 0.006% O, and the balance consists of Fe and impurities. Therefore, the steel plate according to the present invention has good low temperature toughness not only at the fusion line vicinity part and the boundary with a base material in the HAZ but also in the base material and weld metal.

Abstract: The present invention provides an induction-hardened hollow driving shaft that comprises, as a raw material, a steel pipe that contains, by mass %, 0.30 to 0.47% C, 0.5% or less Si, 0.3 to 2.0% Mn, 0.018% or less P, 0.015% or less S, 0.15 to 1.0% Cr, 0.001 to 0.05% Al, 0.005 to 0.05% Ti, 0.004% or less Ca, 0.01% or less N, 0.0005 to 0.005% B and 0.0050% or less O (oxygen) and the balance Fe and impurities and of which Beff defined by an equation (a) or (b) below is 0.0001 or more, wherein a prior austenite grain size number (JIS G0551) after the hardening is 9 or more. Here, in the case of Neff=N?14×Ti/47.9?0, Beff=B×10.8×(N?14×Ti/47.9)/14 . . . (a), and, in other cases, Beff=B . . . (b). According to the present invention, a hollow driving shaft that is simultaneously provided with excellent cold workability, hardenability, toughness and torsional fatigue strength and can exert stable fatigue lifetime can be obtained and can be widely utilized.

Abstract: Embodiments of the present application are directed towards steel compositions that provide improved properties under corrosive environments. Embodiments also relate to protection on the surface of the steel, reducing the permeation of hydrogen. Good process control, in terms of heat treatment working window and resistance to surface oxidation at rolling temperature, are further provided.

Abstract: An age hardenable, martensitic steel alloy that provides high strength, high toughness, and good low cycle fatigue life and a method of making same are disclosed. The alloy comprises a matrix having a weight percent composition consisting essentially of about Carbon ?0.2-0.36 Manganese 0.20 max. Silicon 0.10 max. Phosphorus 0.01 max. Sulfur 0.004 max. Chromium ?1.3-4 Nickel ??10-15 Molybdenum 0.75-2.7 Cobalt ??8-22 Aluminum 0.01 max. Titanium 0.02 max. Calcium 0.001 max. and the balance being iron and usual impurities. The alloy further contains a plurality of inclusions dispersed in the alloy matrix. The inclusions comprise calcium compounds that are about 0.4 ?m to about 7.0 ?m in major dimension, they have a median size of at least about 1.6 ?m in major dimension, and the inclusions contain essentially no rare earth elements.

Abstract: There is provided a component for machine structure having a hardened layer through an induction hardening in at least a part thereof, and more improving fatigue strengths as compared with the conventional ones, in which the hardened layer has a hardness Hv of not less than 750 and an average grain size of prior austenite grains is not more than 7 ?m over a full thickness of the hardened layer.

Abstract: The present invention relates to an austenitic free-cutting stainless steel, containing: by weight percent, 0.500% or less of C; 0.01 to 5.00% of Si; 0.01 to 10.00% of Mn; 5.00 to 25.00% of Ni; 7.50 to 30.00% of Cr; 0.300% or less of N; more than 0.0100% but not more than 0.1000% of 0; 0.0020 to 0.1000% of B; 0.300% or less of Al; and the remainder of Fe and inevitable impurities, the steel satisfying the following formula (1): 0.68?[O]/[B]?2.50 ??(1) in which [O] represents the content of O and [B] represents the content of B.

Abstract: A process for making an article with ballistic protective effect and an article obtainable thereby, as well as a method of providing an object with ballistic protection provided by a corresponding material. The alloys used for making the article comprise the elements C, Si, Mn, Cr, Ni, Mo and V within certain concentration ranges and contain a limited amount of impurities. This abstract is neither intended to define the invention disclosed in this specification nor intended to limit the scope of the invention in any way.

Abstract: The present invention provides a steel sheet excellent in workability, which may be used for components of an automobile or the like, and a method for producing the same. More specifically, according to one exemplary embodiment of the present invention, a steel sheet excellent in workability, including in mass, 0.08 to 0.25% C, 0.001 to 1.5% Si, 0.01 to 2.0% Mn, 0.001 to 0.06% P, at most 0.05% S, 0.001 to 0.007% N, 0.008 to 0.2% Al, at least 0.01% Fe. The steel sheet having an average r-value of at least 1.2, an r-value in the rolling direction of at least 1.3, an r-value in the direction of 45 degrees to the rolling direction of at least 0.9, and an r-value in the direction of a right angle to the rolling direction of at least 1.2.

Abstract: Method for reducing the segregated seams of a steel which has high mechanical strength and high wear resistance and whose composition comprises by weight: 0.30%?C?1.42%; 0.05%?Si?1.5%; Mn?1.95%; Ni?2.9%; 1.1%?Cr?7.9%; 0.61%?Mo?4.4%; optionally V?1.45%, Nb?1.45%, Ta?1.45% and V+Nb/2+Ta/4?1.45% ; less than 0.1% of boron, less than 0.19% of (S+Se/2+Te/4), less than 0.01% of calcium, less than 0.5% of rare earths, less than 1% of aluminum, less than 1% of copper; the balance being iron and impurities resulting from the production operation. The composition further complies with: 800?D?1150 with D=540(C)0.25+245 (Mo+3 V+1.5 Nb+0.75 Ta)0.30+125 Cr0.20+15.8 Mn+7.4 Ni+18 Si. According to the method, the molybdenum is completely or partially replaced with double the proportion of tungsten so that W>0.21%, and Ti, Zr, C are adjusted so that, after adjustment, Ti+Zr/2?0.2 W, (Ti+Zr/2)×C?0.07, Ti+Zr/2?1.49% and D is unchanged at approximately 5%. Steel obtained and method for producing a steel workpiece.

Abstract: Disclosed herein is a steel for high-speed cold working which exhibits good cold workability during working and also exhibits high hardness after working. The steel for high-speed cold working contains C: 0.03 to 0.6% (by mass), Si: 0.005 to 0.6%, Mn: 0.05 to 2%, P: no more than 0.05% (excluding 0%), S: no more than 0.05% (excluding 0%), and N: no more than 0.04% (excluding 0%), with the remainder being iron and inevitable impurities and the amount of dissolved nitrogen in the steel being no less than 0.006%.

Abstract: A steel plate has a C content between 0.05 to 0.18% by mass (hereinafter, content will be expressed simply in “%”), a Si content between 0.10 to 0.50%, a Mn content between 1.2 to 2.0%, an Al content between 0.01 to 0.10%, a Cr content between 0.05 to 0.30% and a V content between 0.01 to 0.05%, and meets a condition expressed by expression (1). 6.7[Cr]+4.5[Mn]+3.5[V]?7.2% ??(1) where [Cr], [Mn] and [V] represent a Cr content, a Mn content and a V content in percent by mass, respectively. The strength reduction of the steel sheet is small even if the steel sheet is subjected for a long time to a stress relief annealing process after being processed by welding. Cracks do not form in the steel plate when the steel plate is welded.

Abstract: A hot forged non-heat treated steel for induction hardening, comprising by mass percent, C: 0.35 to 0.45%, Si: 0.20 to 0.60%, Mn: 0.40 to 0.80%, S: 0.040 to 0.070%, Cr: 0.10 to 0.40%, Ti: 0.020 to 0.100%, Ca: 0.0005 to 0.0050%, B: 0.0005 to 0.0030%, O: 0.0015 to 0.0050%, Mo: 0 to 0.05%, P: 0.025% or less, V: 0.03% or less, Al: 0.009% or less and N: 0.0100% or less, and the balance being Fe and impurities, with Fn1=C+(Si/10)+(Mn/5)+(5Cr/22)+1.65V?(5/7S)+1.51×(Ti?3.4N)?0.63, Ca/O?1.0, and 25.9×Fn1+27.5×(Ti?3.4N)?7.9?5.7, has more excellence in the machinability than a conventional steel and also has fatigue strength equal to or more than that of a conventional steel, while using the steel product in a hot forged state as a starting material.

Abstract: Provided is free cutting alloy excellent in machinability, preserving various characteristics as alloy. The free cutting alloy contains: one or more of Ti and Zr as a metal element component; and C being an indispensable element as a bonding component with the metal element component, wherein a (Ti,Zr) based compound including one or more of S, Se and Te is formed in a matrix metal phase. The free cutting alloy is more excellent in machinability, preserving various characteristics as alloy at similar levels to a conventional case. The effect is especially conspicuous, for example, when a compound expressed in a chemical form of (Ti,Zr)4C2(S,Se,Te)2 as the (Ti,Zr) based compound is formed at least in a dispersed state in the alloy structure.

Abstract: There is provided a high-stiffness high-strength thin steel sheet having a tensile strength of not less than 590 MPa and a Young's modulus of not less than 225 GPa, which comprises C: 0.02-0.15%, Si: not more than 1.5%, Mn: 1.5-4.0%, P: not more than 0.05%, S: not more than 0.01%, Al: not more than 1.5%, N: not more than 0.01% and Nb: 0.02-0.40% as mass %, provided that C, N and Nb contents satisfy 0.01?C+(12/14)×N?(12/92.9)×Nb?0.06 and N?(14/92.9)×(Nb?0.01) and the remainder being substantially iron and inevitable impurities, and has a texture comprising a ferrite phase as a main phase and having a martensite phase at an area ratio of not less than 1%.

Abstract: The present invention is to provide a free-cutting steel capable of suppressing production of coarse inclusions, and having a high fatigue strength and a desirable machinability. The free-cutting steel aimed at solving the foregoing problems consists essentially of, in % by mass, C: 0.1-0.5%, Si: 0.05-2.5%, Mn: 0.1-3.5%, S: 0.0005-0.004%, Al: 0.01-0.06%, Ti: 0.003-0.01%, O: up to 0.0015%, N: 0.003-0.01%, Bi: 0.015-0.025%, and the balance of Fe and inevitable impurities, wherein the formula (1) below is satisfied: ?4.8?log(([N]?0.0015)×[Ti]0.98)??4.3.

Abstract: A steel for steel pipes which comprises, on the percent by mass basis, C: 0.2 to 0.7%, Si: 0.01 to 0.8%, Mn: 0.1 to 1.5%, S: 0.005% or less, P: 0.03% or less, Al: 0.0005 to 0.1%, Ti: 0.005 to 0.05%, Ca: 0.0004 to 0.005%, N: 0.007% or less, Cr: 0.1 to 1.5%, Mo: 0.2 to 1.0%, Nb: 0 to 0.1%, Zr: 0 to 0.1%, V: 0 to 0.5% and B: 0 to 0.005%, with the balance being Fe and impurities, in which non-metallic inclusions containing Ca, Al, Ti, N, O, and S are present, and in the said inclusions (Ca %)/(Al %) is 0.55 to 1.72, and (Ca %)/(Ti %) is 0.7 to 19 can be used as a raw material for oil country tubular goods, being used at a greater depth and in severer corrosive circumstances, such as casings and tubings for oil and/or natural gas wells, drilling pipes and drilling collars for excavation, and the like.

Abstract: A lead-free steel for machine structural use with excellent machinability and low strength anisotropy, which does not contain Pb and is equal to or higher than a conventional Pb-containing free cutting steel in properties, is provided. This steel includes, on the weight basis, C: 0.10 to 0.65%; Si: 0.03 to 1.00%; Mn: 0.30 to 2.50%; S: 0.03 to 0.35%; Cr: 0.1 to 2.0%; Al: less than 0.010%; Ca: 0.0005 to 0.020%; Mg: 0.0003 to 0.020%; O: less than 20 ppm; and the balance being Fe and inevitable impurities.

Abstract: A sulfur-containing free-cutting steel for machine structural use, containing, in weight percent, 0.10 to 0.55% of C, 0.05 to 1.00% of Si, 0.30 to 2.50% of Mn, not more than 0.15% of P, 0.050 to 0.350% of S, more than 0.010% but not more than 0.020% of Al, 0.015 to 0.200% of Nb, 0.0015 to 0.0150% of O, and not more than 0.02% of N, and further containing, in weight percent, at least one selected from the group consisting of 0.03 to 0.50% of V, 0.02 to 0.20% of Ti and 0.01 to 0.20% of Zr, wherein the ratio S/O of the S content to the O content is 15 to 120, and at least one selected from the group consisting of an oxide, a carbide, a nitride and a carbonitride of Nb(see FIG. 1) acts as nuclei for precipitation of MnS type inclusions.

Abstract: The composition of inclusions and the S concentration in steel are controlled in a manner such that, among the CaO-containing oxide inclusions present in a Ca-containing steel, an equilibrium S soluble amount (% S inc.) of at least 80% of the oxide inclusion particles having a particle diameter of 2 ?m or more are about 0.03 wt % or less, thereby inhibiting rust formation due to the inclusions, thus solving a problem which has long been of concern in Ca-containing steels.

Abstract: A steel for machine structural use which comprises, on the percent by mass basis, C: 0.1 to 0.6%, Si: 0.01 to 2.0%, Mn: 0.2 to 2.0%, S: 0.005 to 0.20%, P: not more than 0.1%, Ca: 0.0001 to 0.01%, N: 0.001 to 0.02% and Al: not more than 0.1%, with the balance being Fe and impurities, with a value of [Ca]e defined by [Ca]e=T.[Ca]?(T.[O]/(O)ox)×(Ca)ox of not more than 5 ppm or with a proportion of MnO contained in oxide inclusions of not more than 0.05 and a value of Ca/O of not more than 0.8 is excellent in machinability and, therefore, it can be used as a steel stock for various machine structural steel parts, such as in industrial machinery, construction machinery and conveying machinery such as automobiles. It is substantially free of Pb, hence suited for use as a steel friendly to the global environment. [Ca]e is the effective Ca concentration index (ppm by mass), T.[Ca] and T.

Abstract: Disclosed is a free machining steel for machine structural use, which can realize very good chip disposability without incorporation of any harmful material such as lead (Pb). This free machining steel is a hot rolled or hot forged free machining steel having improved chip disposability. The free machining steel comprises, by mass, carbon (C): 0.01 to 0.70%, silicon (Si): 0.05 to 2.00%, manganese (Mn): 0.20 to 3.50%, calcium (Ca): 0.0003 to 0.01%, sulfur (S): 0.020 to 0.300%, aluminum (Al): 0.002 to 0.300%, nitrogen (N): 0.003 to 0.035%, and oxygen (O): 0.0010 to 0.0080% with the balance consisting of iron (Fe) and unavoidable impurities. The steel comprises sulfides having the major axis of from 0.5 &mgr;m to 20 &mgr;m, exclusive, and comprising MnS as the main component, in a number of not less than 30% of the total number of sulfides. The steel also comprises oxide inclusions having the major axis of from 0.

Abstract: The invention provides a steel for machine structural use, which is excellent in machinability, comprising, in percent by mass, C: 0.1-0.6%. Si: 0.01-2.0%, Mn: 0.2-2.0%, S: 0.005-0.2%, Al: not more than 0.009%, Ti: not less than 0.001% but less than 0.04%, Ca: 0.0001-0.01%, O (oxygen): 0.0010-0.01%, and N: not more than 0.02% and satisfying the following relations (1) to (3): n0/S (%)≧2500  (1) n1/n0≦0.1  (2) n2≧10  (3) where n0: total number of sulfide inclusions not smaller than 1 &mgr;m per mm2 of a cross section parallel to the direction of rolling (number/mm2); n1: number of MnS inclusions having not smaller than 1 &mgr;m and containing not less than 1.