The martensitic stainless steel seamless pipe according to the present disclosure has a chemical composition containing, in mass %, C: 0.001 to 0.050%, Si: 0.05 to 1.00%, Mn: 0.05 to 2.00%, P: 0.030% or less, S: 0.0100% or less, Al: 0.005 to 0.100%, N: 0.020% or less, Ni: 1.00 to 9.00%, Cr: 8.00 to 16.00%, Cu: 3.50% or less, Mo: 1.00 to 5.00%, W: 0.01 to 0.30%, V: 0.010 to 1.500%, and Co: 0.001 to 0.500%, and also containing one or more elements selected from the group consisting of Ca, Mg, B, and rare earth metal, with the balance being Fe and impurities, and has a yield strength of 655 MPa or more.

A duplex stainless steel having excellent carbon dioxide corrosion resistance, excellent sulfide stress corrosion cracking resistance, and excellent sulfide stress cracking resistance. The duplex stainless steel comprises, by mass %, C: 0.03% or less, Si: 1.0% or less, Mn: 0.10 to 1.5%, P: 0.030% or less, S: 0.005% or less, Cr: 20.0 to 30.0%, Ni: 5.0 to 10.0%, Mo: 2.0 to 5.0%, Cu: 2.0 to 6.0%, N: less than 0.07%, at least one selected from Al: 0.05 to 1.0%, Ti: 0.02 to 1.0%, and Nb: 0.02 to 1.0%, and the balance being Fe and unavoidable impurities, and has a structure that is 20 to 70% austenite phase, and 30 to 80% ferrite phase in terms of a volume fraction.

Method of manufacturing zirconium alloy tubular products containing (wt. %): niobium—0.9-1.7; iron—0.04-0.10; oxygen—0.03-0.10; silicon—less than 0.02, carbon—less than 0.02, and zirconium—as the base of the alloy. This includes an ingot melting by multiple vacuum arc remelting, mechanical processing of the ingot, heating, hot working of the ingot, subsequent mechanical processing for the production of tubular billets, heat treatment of the tubular billets, application of a protective coating and heating to a hot pressing temperature, hot pressing, removal of the protective coating, multi-stage cold radial forging, vacuum thermal treatment, multiple cold rolling runs with a total deformation degree of 50-80-% per run and a tubular coefficient of Q=1.0-2.7 with intermediate vacuum thermal treatment after each cold rolling operation, and final vacuum thermal treatment of the resulting tubular products carried out at the final size with subsequent final finishing operations.

Manufacturing method for tubular products made of zirconium-based alloy includes melting an ingot by multiple vacuum arc remelting, mechanical processing of the ingot, heating, multi-stage hot forging of the ingot for production of a forged piece, subsequent mechanical processing of the forged piece for production of the a round-profile blank, manufacturing of tubular billets, their quenching and tempering, application of a protective coating, heating to a hot pressing temperature, hot pressing, removal of the protective coating, vacuum thermal treatment, multiple cold rolling steps in order to produce tubular products, with intermediate vacuum thermal treatment after each cold rolling, and a final vacuum thermal treatment being carried out at a final size with subsequent final finishing operations. The tubular products can be used as the structural components of a core in water-cooled nuclear reactors. The method can provide increased processibility, high strength, and corrosion resistance of tubular products.

Manufacturing method for zirconium alloy tubular products containing (% wt.): niobium—0.9-1.7; iron—0.10-0.20; oxygen—0.10-0.20; silicon—less than 0.02, carbon—less than 0.02, zirconium—the alloy base. The method includes melting an ingot by multiple vacuum arc remelting, mechanical processing of the ingot, heating, multi-stage hot forging for production of the forged piece, subsequent mechanical processing of the forged piece for production of tubular billets with vacuum thermal treatment, application of a protective coating, heating to a hot pressing temperature, hot pressing, removal of the protective coating, vacuum thermal treatment, multiple cold rolling steps with a total deformation degree of 58-74% per run and a tubular coefficient of Q=1.18-2.01, with intermediate vacuum thermal treatment in order to produce tubular products, and final vacuum thermal treatment being carried out at the final size with subsequent final finishing operations.

Manufacturing method for zirconium alloy tubular products containing (% wt.): niobium—0.9-1.7; iron—0.10-0.20; oxygen—0.10-0.20; silicon—less than 0.02, carbon—less than 0.02, zirconium—the alloy base. The method includes melting an ingot by multiple vacuum arc remelting, mechanical processing of the ingot, heating, multi-stage hot forging for production of the forged piece, subsequent mechanical processing of the forged piece for production of tubular billets with vacuum thermal treatment, application of a protective coating, heating to a hot pressing temperature, hot pressing, removal of the protective coating, vacuum thermal treatment, multiple cold rolling steps with a total deformation degree of 58-74% per run and a tubular coefficient of Q=1.18-2.01, with intermediate vacuum thermal treatment in order to produce tubular products, and final vacuum thermal treatment being carried out at the final size with subsequent final finishing operations.

The steel pipe according to the present disclosure contains a chemical composition consisting of, in mass %, C: more than 0.50 to 0.65%, Si: 0.05 to 0.50%, Mn: 0.05 to 1.00%, P: 0.025% or less, S: 0.0050% or less, Al: 0.005 to 0.100%, Cr: 0.30 to 1.50%, Mo: 0.25 to 3.00%, Ti: 0.002 to 0.050%, N: 0.0010 to 0.0100% and O: 0.0030% or less, with the balance being Fe and impurities. The steel pipe contains an amount of dissolved C within a range of 0.010 to 0.060 mass %. The tensile yield strength in the axial direction and the circumferential direction is 862 to 1069 MPa, and the yield ratio in the axial direction is 90% or more. The tensile yield strength in the circumferential direction is 30 to 80 MPa higher than the compressive yield strength in the circumferential direction.

The steel pipe according to the present disclosure contains a chemical composition consisting of, in mass %, C: more than 0.50 to 0.65%, Si: 0.05 to 0.50%, Mn: 0.05 to 1.00%, P: 0.025% or less, S: 0.0050% or less, Al: 0.005 to 0.100%, Cr: 0.30 to 1.50%, Mo: 0.25 to 3.00%, Ti: 0.002 to 0.050%, N: 0.0010 to 0.0100% and O: 0.0030% or less, with the balance being Fe and impurities. The steel pipe contains an amount of dissolved C within a range of 0.010 to 0.060 mass %. The tensile yield strength in the axial direction and the circumferential direction is 862 to 1069 MPa, and the yield ratio in the axial direction is 90% or more. The tensile yield strength in the circumferential direction is 30 to 80 MPa higher than the compressive yield strength in the circumferential direction.

A sliding element, in particular a piston ring, includes a base material of martensitic or austenitic stainless steel having a chromium content of at least 6.0% by mass and a nitrided layer having a surface hardness of up to 950 HV1. A method of producing such a sliding layer is also provided.

Provided herein is a stainless steel seamless pipe having a composition that contains, in mass %, C: 0.06% or less, Si: 1.0% or less, Mn: 0.01% or more and 1.0% or less, P: 0.05% or less, S: 0.005% or less, Cr: 15.2% or more and 18.5% or less, Mo: 1.5% or more and 4.3% or less, Cu: 1.1% or more and 3.5% or less, Ni: 3.0% or more and 6.5% or less, Al: 0.10% or less, N: 0.10% or less, O: 0.010% or less, and Sn: 0.001% or more and 1.000% or less, and in which C, Si, Mn, Cr, Ni, Mo, Cu, and N satisfy the predetermined formula, and the balance is Fe and incidental impurities, the stainless steel seamless pipe having a microstructure containing 30% or more martensitic phase, 65% or less ferrite phase, and 40% or less retained austenite phase by volume.