Invention Grant
- Patent Title: Stainless steel for oil well, stainless steel pipe for oil well, and method of manufacturing stainless steel for oil well
- Patent Title (中): 油井不锈钢，油井不锈钢管，油井不锈钢制造方法
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Application No.: US14793916Application Date: 2015-07-08
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Publication No.: US09322087B2Publication Date: 2016-04-26
- Inventor: Hideki Takabe , Kunio Kondo , Hisashi Amaya , Taro Ohe , Yohei Otome
- Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION
- Applicant Address: JP Tokyo
- Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
- Current Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
- Current Assignee Address: JP Tokyo
- Agency: Clark & Brody
- Priority: JP2009-119990 20090518
- Main IPC: C21D8/00
- IPC: C21D8/00 ; C22C38/50 ; C21D8/02 ; C21D8/10 ; C21D9/08 ; C22C38/00 ; C22C38/02 ; C22C38/04 ; C22C38/06 ; C22C38/42 ; C22C38/44 ; F16L9/02 ; C21D6/00 ; C22C38/46 ; C22C38/48
Abstract:
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 ≧25.5 (1) −8 ≦30(C+N)+0.5Mn+Ni+Cu/2+8.2−1.1(Cr+Mo) ≦−4 (2)
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