The steel material according to the present disclosure consists of, in mass%, C: 0.15 to 0.45%, Si: 0.05 to 1.00%, Mn: 0.05 to less than 0.80%, P: 0.030% or less, S: 0.0100% or less, Al: 0.100% or less, Cr: 0.30 to 1.50%, Mo: 0.25 to 2.00%, Ti: 0.001 to 0.015%, N: 0.0100% or less, O: 0.0050% or less, V: 0 to 0.05%, Nb: 0 to 0.010%, B: 0 to less than 0.0005%, Ca: 0 to 0.0100%, Mg: 0 to 0.0100%, and rare earth metal: 0 to 0.0100%, with the balance being Fe and impurities. In the steel material, the grain size number of prior-austenite grains is less than 7.0, Formula (1) to Formula (4) described in the specification are satisfied, the yield strength is 896 MPa or more, and the absorbed energy at -10° C. is 95 J or more.

Special usage steels, particularly those intended to be in contact with combustion fumes, are described. Tubular components produced based on such steels are also described. The steel both is resistant to the coking phenomenon and has improved mechanical performances. The steel contains in percentage by weight from 0.08 to 0.15% carbon, from 0.4 to 0.8% manganese, from 1.5 to 2.5% silicon, from 0.5 to 2% copper, from 8 to 10% chrome, from 0.5 to 3% nickel, from 0.01 to 0.07% nitrogen, from 0.8 to 1.1% molybdenum, with the remainder being iron and impurities.

A low-alloy steel has a composition including, by mass %, C: more than 0.45 and up to 0.65%; Si: 0.05 to 0.50%; Mn: 0.10 to 1.00%; P: up to 0.020%; S: up to 0.0020%; Cu: up to 0.1%; Cr: 0.40 to 1.50%; Ni: up to 0.1%; Mo: 0.50 to 2.50%; Ti: up to 0.01%; V: 0.05 to 0.25%; Nb: 0.005 to 0.20%; Al: 0.010 to 0.100%; B: up to 0.0005%; Ca: 0 to 0.003%; 0: up to 0.01%; N: up to 0.007%; and other elements. A microstructure consists of tempered martensite and retained austenite<2% in volume fraction, crystal grain size number being 9.0 or larger, number density of carbonitride-based inclusions with grain diameter of 50 μm or larger being 10 inclusions/100 mm.sup.2 or smaller, and yield strength being 965 MPa or higher.

Provided is steel for nitrocarburizing with excellent surface fatigue strength. The steel has a nitride compound layer with a thickness of 5.0 μm to 30.0 μm and a hardened layer in an order from a steel surface to steel inside, where a thickness of a porous layer on an outermost surface of the compound layer is 3.0 μm or less and 40.0% or less of a compound layer's thickness, the hardened layer has hardness of HV600 or more, HV400 or more and HV250 or more at 50 μm inward from the steel surface, from the steel surface to the steel inside of 400 μm, and from the steel surface to the steel inside of 600 μm, respectively, an unhardened portion excluding the compound and hardened layers has a predetermined chemical composition, and the hardened layer has a chemical composition with a higher N content than the unhardened portion.

A high-strength thick-walled electric resistance welded steel pipe has excellent low-temperature toughness and excellent HIC resistance and a yield strength of 400 MPa or more. The steel has a chemical composition consisting of C: 0.025% to 0.084%, Si: 0.10% to 0.30%, Mn: 0.70% to 1.80%, controlled amounts of P, S, Al, N, and O, Nb: 0.001% to 0.065%, V: 0.001% to 0.065%, Ti: 0.001% to 0.033%, and Ca: 0.0001% to 0.0035% on a mass percent basis and the remainder being Fe and incidental impurities, and satisfies Pcm of 0.20 or less.

A lens alignment system and method is disclosed. The disclosed system/method integrates one or more lens retaining members/tubes (LRM/LRT) and focal length spacers (FLS) each comprising a metallic material product (MMP) specifically manufactured to have a thermal expansion coefficient (TEC) in a predetermined range via selection of the individual MMP materials and an associated MMP manufacturing process providing for controlled TEC. This controlled LRM/LRT TEC enables a plurality of optical lenses (POL) fixed along a common optical axis (COA) by the LRM/LRT to maintain precise interspatial alignment characteristics that ensure consistent and/or controlled series focal length (SFL) within the POL to generate a thermally neutral optical system (TNOS). Integration of the POL using this LRM/LRT/FLS lens alignment system reduces the overall TNOS implementation cost, reduces the overall TNOS mass, reduces TNOS parts component count, and increases the reliability of the overall optical system.

A high-strength seamless steel pipe for oil country tubular goods comprising, by mass %, C: 0.20% to 0.50%, Si: 0.05% to 0.40%, Mn: 0.3% to 0.9%, P: 0.015% or less, S: 0.005% or less, Al: 0.005% to 0.1%, N: 0.006% or less, Mo: more than 1.0% to 3.0% or less, V: 0.01% to less than 0.05%, Nb: 0.001% to less than 0.01%, B: 0.0003% to 0.0030%, O: 0.0030% or less, and Ti: 0.003% to 0.025%, and wherein Ti/N: 2.0 to 5.0 is satisfied, a volume fraction of a tempered martensitic is 95% or more, prior austenite grains have a grain size number of 8.5 or more, and in a cross-section perpendicular to a rolling direction, the number of nitride-based inclusions having a grain size of 4 μm or more is 100 or less per 100 mm.sup.2, the number of nitride-based inclusions having a grain size of less than 4 μm is 1000 or less per 100 mm.sup.2, the number of oxide-based inclusions having a grain size of 4 μm or more is 40 or less per 100 mm.sup.2, and the number of oxide-based inclusions having a grain size of less than 4 μm is 400 or less per 100 mm.sup.2.

A high-strength seamless steel pipe for oil country tubular goods comprising, by mass %, C: 0.20% to 0.50%, Si: 0.05% to 0.40%, Mn: more than 0.6% to 1.5% or less, P: 0.015% or less, S: 0.005% or less, Al: 0.005% to 0.1%, N: 0.006% or less, Mo: more than 1.0% to 3.0% or less, V: 0.05% to 0.3%, Nb: 0.001% to 0.020%, B: 0.0003% to 0.0030%, O: 0.0030% or less, and Ti: 0.003% to 0.025%, and wherein Ti/N: 2.0 to 5.0 is satisfied, a volume fraction of a tempered martensitic is 95% or more, prior austenite grains have a grain size number of 8.5 or more, and in a cross-section perpendicular to a rolling direction, the number of nitride-based inclusions having a grain size of 4 m or more is 100 or less per 100 mm.sup.2, the number of nitride-based inclusions having a grain size of less than 4 μm is 1000 or less per 100 mm.sup.2, the number of oxide-based inclusions having a grain size of 4 μm or more is 40 or less per 100 mm.sup.2, and the number of oxide-based inclusions having a grain size of less than 4 μm is 400 or less per 100 mm.sup.2, and methods of producing the same.

Austenitic stainless steels excellent in flexibility are provided. The austenitic stainless steel excellent in flexibility includes, by weight percent, 0.1 to 0.65% of Si, 1.0 to 3.0% of Mn, 6.5 to 10.0% of Ni, 16.5 to 18.5% of Cr, 6.0% or less of Cu (excluding 0), 0.13% or less of (C+N) (excluding 0), and the remainder including Fe and unavoidable impurities, wherein the work hardening formula H1 defined by the following formula is 300 or less.

H1=−459+79.8Si−10.2Mn−8.16Ni+48.0Cr−13.2Cu+623(C+N).

A high temperature iron-chromium-aluminium (FeCrAl) alloy tube extending along a longitudinal axis, wherein the tube is formed from a continuous strip of a high temperature FeCrAl alloy and comprises a helical welded seam. The high temperature FeCrAl alloy tube is manufactured by feeding a continuous strip of the high temperature FeCrAl alloy toward a tube shaping station, helically winding the strip such that long edges of the strip abut each other and a rotating tube moving forward in a direction parallel to its longitudinal axis is formed, and continuously joining said abutting long edges together in a welding process directly when the tube is formed, whereby a welded tube comprising a helical welded seam is obtained.