Nippon Steel & Sumitomo Metal Corporation

Nippon Steel Corporation

Sumitomo Metal Industries, Inc.

Yohei Otome

Kunio Kondo

Taro Ohe

Yuji Arai

Masaaki Igarashi

Kazuhiro Shimoda

Hisashi Amaya

Hideki Takabe

Hiroki Kamitani

Tomohiko Omura

Shinji Yoshida

Hirokazu Okada

Yusaku Tomio

Atsushi Soma

Masayuki Sagara

Masanao Seo

Taro Oe

Nobuaki Komatsubara

Shinjiro Nakatsuka

The steel material according to the present disclosure has a chemical composition consisting of, in mass %, C: 0.15 to 0.45%, Si: 0.05 to 1.00%, Mn: 0.01 to 1.00%, P: 0.030% or less, S: 0.0050% or less, Al: 0.005 to 0.100%, Cr 0.60 to 1.80%, Mo: 0.80 to 2.30%, Ti: 0.002 to 0.020%, V: 0.05 to 0.30%, Nb: 0.002 to 0.100%, B: 0.0005 to 0.0040%, Cu: 0.01 to 0.50%, Ni: 0.01 to 0.50%, N: 0.0020 to 0.0100% and O: 0.0020% or less, with the balance being Fe and impurities. The number density of BN in the steel material is 10 to 100 particles/100 μm. The yield strength of the steel material is 758 MPa or more.

Steel material and method for producing steel material

A steel material according to the present disclosure has a chemical composition consisting of, in mass %: C: 0.15 to 0.45%, Si: 0.05 to 1.00%, Mn: 0.01 to 1.00%, P: 0.030% or less, S: 0.0050% or less, Al: 0.005 to 0.100%, Cr 0.55 to 1.10%, Mo: 0.70 to 1.00%, Ti: 0.002 to 0.020%, V: 0.05 to 0.30%, Nb: 0.002 to 0.100%, B: 0.0005 to 0.0040%, N: 0.0100% or less, O: less than 0.0020%, and the balance being Fe and impurities, and satisfying Formula (1) described in the specification. A grain diameter of a prior-austenite grain is 15.0 μm or less, and an average area of precipitate which is precipitated in a prior-austenite grain boundary is 12.5×10μmor less. A yield strength is 758 to 862 MPa.

Steel material suitable for use in sour environment

A stainless steel for oil wells which has excellent high-temperature corrosion resistance and can stably obtain a strength of not less than 758 MPa is provided. The stainless steel for oil wells contains, by masse, C: not more than 0.05%, Si: not more than 1.0%, Mn: 0.01 to 1.0%, P: not more than 0.05%, S: less than 0.002%, Cr: 16 to 18%, Mo: 1.8 to 3%, Cu: 1.0 to 3.5%, Ni: 3.0 to 5.5%, Co: 0.01 to 1.0%, Al: 0.001 to 0.1%, O: not more than 0.05%, and N: not more than 0.05%, the balance being Fe and impurities, and satisfies Formulas (1) and (2):Cr+4Ni+3Mo+2Cu&#x2267;44&#x2003;&#x2003;(1)Cr+3Ni+4Mo+2Cu/3&#x2266;46&#x2003;&#x2003;(2)

Stainless steel for oil wells and stainless steel pipe for oil wells

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 &#x2267;&#x2003;&#x2003;()&#x2212;(C+N)+Mn+Ni+Cu/(Cr+Mo) &#x2266;&#x2212;&#x2003;&#x2003;()

Stainless steel for oil well, stainless steel pipe for oil well, and method of manufacturing stainless steel for oil well

A high-strength stainless steel for oil well having corrosion resistance excellent in a high-temperature environment, having excellent SSC resistance at normal temperature, and having better workability than 13% Cr steels has a chemical composition containing, by mass percent, C: at most 0.05%, Si: at most 1.0%, Mn: at most 0.3%, P: at most 0.05%, S: less than 0.002%, Cr: over 16% and at most 18%, Mo: 1.5 to 3.0%, Cu: 1.0 to 3.5%, Ni: 3.5 to 6.5%, Al: 0.001 to 0.1%, N: at most 0.025%, and O: at most 0.01%, the balance being Fe and impurities, a microstructure containing a martensite phase, 10 to 48.5%, by volume ratio, of a ferrite phase and at most 10%, by volume ratio, of a retained austenite phase, yield strength of at least 758 MPa and uniform elongation of at least 10%.

High-strength stainless steel for oil well and high-strength stainless steel pipe for oil well

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&#x2267;25.5&#x2003;&#x2003;(1)&#x2212;8&#x2266;30(C+N)+0.5Mn+Ni+Cu/2+8.2&#x2212;1.1(Cr+Mo)&#x2266;&#x2212;4&#x2003;&#x2003;(2)

A high strength Cr&#x2014;Ni alloy material excellent in hot workability and stress corrosion cracking resistance, and seamless pipe for oil well application which consists of, by mass percent, C: 0.05% or less, Si: 0.05 to 1.0%, Mn: 0.01% or more and less than 3.0%, P: 0.05% or less, S: 0.005% or less, Cu: 0.01 to 4%, Ni: 25% or more and less than 35%, Cr: 20 to 30%, Mo: 0.01% or more and less than 4.0%, N: 0.10 to 0.30%, Al: 0.03 to 0.30%, O (oxygen): 0.01% or less, and REM (rare earth metal): 0.01 to 0.20% with the balance being Fe and impurities, and also satisfies the conditions in the following formula (1)./REM&#x2266;0.40&#x2003;&#x2003;formula (1)where P, N, and REM in the formula (1) respectively denote the contents (mass %) of P, N, and REM. The high strength Cr&#x2014;Ni alloy material may further contain one or more types of W, Ti, Nb, Zr, V, Ca, and Mg, instead of part of Fe.

High strength Cr-Ni alloy material and seamless pipe for oil well

Growing community of inventors

Amagasaki, Japan

Yohei Otome