Nkk Tubes

Nkk Corporation

Tenaris Connections B.v.

Yusuke Minami

Shuji Hashizume

Tatsuo Ono

Hitoshi Iijima

Tatsuro Katsumura

Takemi Yamada

Yoshiichi Ishizawa

Toshihiko Fukui

Giuseppe Cumino

Motohisa Yoshida

Masahiko Yasukawa

Tomomi Taniguchi

Yu Yamamoto

Paola Mariani

Tatsuo Takaoka

The present invention provides a high-chromium heat-resistant steel. The steel contains in mass %, C: 0.08% to 0.13%; Si: 0.15% to 0.45%; Mn: 0.1% to 1.0%; Ni: 0.01% to 0.5%; Cr: 10.0% to 11.5%; Mo: 0.3% to 0.6%; V: 0.10% to 0.25%; Nb: 0.01% to 0.06%; N: 0.015% to 0.07%; B: &#x2264;0.005%, and Al: &#x2264;0.04%. The balance consists of Fe and inevitable impurity elements. The steel shows a martensitic microstructure.

High-chromium heat-resistant steel

A purpose of the present invention is to provide a martensitic stainless steel tube exhibiting excellent performance even in severe corrosive environments in which a partial pressure of hydrogen sulfide exceeds 0.03 bar. Provided is a low C-high Cr alloy steel tube for OCTG (Oil Country Tubular Goods) having minimum yield strength of 862 MPa and excellent corrosion resistance, wherein the steel tube contains, in percent by mass, 0.005 to 0.05% C, 12 to 16% Cr, 1.0% or less Si, 2.0% or less Mn, 3.5 to 7.5% Ni, 1.5 to 3.5% Mo, 0.01 to 0.05% V, 0.02% or less N, and 0.01 to 0.06% Ta and satisfies the relationship in the following formula (1), and the rest comprises Fe and unavoidable impurities.25-25 (% Ni)+5 (% Cr)+25 (% Mo)&#x2267;0&#x2003;&#x2003;(1).

Low C-high Cr 862 MPa-class steel tube having excellent corrosion resistance and a manufacturing method thereof

A purpose of the present invention is to provide a martensitic stainless steel applicable in environments involving both wet carbon dioxide gas and wet hydrogen sulfide and excellent in weldability, manufacturability, and resistance to strain age hardening. Provided is a martensitic stainless steel having excellent corrosion resistance and resistance to strain age hardening comprising, in percent by mass, 0.02% or less of C, 0.02% or less of N, 0.1 to 0.5% of Si, 0.1 to 0.5% of Mn, 10 to 13% Cr, Ni exceeding 5.0% but 8% or less, 1.5 to 3% of Mo, 0.01 to 0.05% of V, 0.16 to 0.30% of Zr, 0.01 to 0.05% of Ta, and the balance of Fe and unavoidable impurities, wherein the martensitic stainless steel satisfies the condition that the sum of the carbon and the nitrogen exceeds 0.02% but 0.04% or less.

Martensitic stainless steel having excellent corrosion resistance

A martensitic stainless steel for inexpensive seamless pipe having 655 MPa yield strength, high toughness and excellent corrosion resistance in high COenvironments, and a method for manufacturing thereof is provided. The steel comprises C: 0.005-0.05%, Si: 0.1-0.5%, Mn: 0.1-2.0%, P: &#x2212;0.05%, S: &#x2212;0.005%, Cr: 10.0-12.5%, Mo: 0.1-0.5%, Ni: 1.5-3.0%, N: &#x2212;0.02%, Al: 0.01-0.1%, by weight, while FI value defined by the formula [FI=Cr+Mo&#x2212;Ni&#x2212;30(C+N)] being 5.00 to 8.49, and balance of substantially Fe. The method comprises the steps of reheating the cooled steel at temperatures from 780&#xb0; C. to 960&#xb0; C., quenching the reheated steel, and then tempering the quenched steel at temperatures from 550&#xb0; C. to 650&#xb0; C.

655 MPa grade martensitic stainless steel having high toughness and method for manufacturing the same

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 &#x3bc;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.

Austenitic stainless steel tube for boiler with excellent resistance to high temperature steam oxidation

A seamless steel tubular product is produced by hot-piercing an alloy-steel billet with a piercing plug to produce a hollow shell and then rolling the hollow shell. Prior to the hot-piercing, a steel sheet is joined to an end surface of the billet into which the plug is to be driven, such that the steel plate may not project beyond the periphery of the billet, the steel plate having a surface area (C) satisfying the equation:

Method for producing a seamless steel tubular product

A high strength martensitic stainless steel contains:

High-strength martensitic stainless steel and method for making the same

A martensitic stainless steel having good corrosion resistance suitable for use in an oil well having 0.08 to 0.25 wt. % C, 14 to 16 wt. % Cr, 1.0 wt. % or less Si, 2.0 wt. % or less Mn, 0.5 to 3.0 wt. % Ni, 0.03 to 0.10 wt. % N, 0.04 wt. % or less P, 0.01 wt. % or less S, 0.1 to 1.0 wt. % Mo, the balance being Fe and inevitable impurities. The Cr, C, Ni and N being in amounts such that 20 wt. % .gtoreq.Cr-12C+0.75 Ni+10N.gtoreq.13 wt. %. The martensitic stainless steel having a content of .delta.-ferrite of 10% or less. The martensitic stainless steel can contain at least one of 0.05 to 0.30 wt. % V and 0.01 to 0.1 wt. % Nb. Also the martensitic stainless steel can contain 0.5 to 3.0 wt. % Cu. Further the martensitic stainless steel can contain 0.5 to 3.0 wt. % Cu, and at least one of 0.05 to 3.0 wt. % V and 0.01 to 0.1 wt. % Nb.

Growing community of inventors

Kawasaki, Japan

Yusuke Minami