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The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.

The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.

Patent No.:

US 12043885 B1

PDFFull Text
Date of Patent:
Jul. 23, 2024

Filed:

Jul. 09, 2019

Seamless steel pipe and method for producing the same

Applicant:

Nippon Steel Corporation, Tokyo, JP;

Inventors:

Daisuke Matsuo, Tokyo, JP;

Yusaku Tomio, Tokyo, JP;

Assignee:

NIPPON STEEL CORPORATION, Tokyo, JP;

Attorney:

Greer, Burns & Crain, Ltd.

Primary Examiner:

Nicholas A Wang

Int. Cl.
CPC ...
C22C 38/50 (2006.01); C21D 8/00 (2006.01); C21D 8/06 (2006.01); C21D 9/08 (2006.01); C22C 38/00 (2006.01); C22C 38/02 (2006.01); C22C 38/04 (2006.01); C22C 38/06 (2006.01); C22C 38/42 (2006.01); C22C 38/44 (2006.01); C22C 38/48 (2006.01);
U.S. Cl.
CPC ...
C22C 38/50 (2013.01); C21D 8/005 (2013.01); C21D 8/065 (2013.01); C21D 9/085 (2013.01); C22C 38/001 (2013.01); C22C 38/002 (2013.01); C22C 38/02 (2013.01); C22C 38/04 (2013.01); C22C 38/06 (2013.01); C22C 38/42 (2013.01); C22C 38/44 (2013.01); C22C 38/48 (2013.01); C21D 2211/001 (2013.01); C21D 2211/005 (2013.01); C21D 2211/008 (2013.01);
Abstract

The chemical composition of the seamless steel pipe contains Cr: 15.00 to 18.00% in mass % and satisfies Formulae (1) and (2). Furthermore, in the microstructure, (I) a total volume ratio of ferrite and martensite is 80% or more, with the balance being retained austenite of a volume ratio of 20% or less, (II) the number of intersections NTin the L-direction observation field of view is 38 or more and NT/NL is 1.80 or more, and further (III) the number of intersections NTin the C-direction observation field of view is 30 or more and NT/NC is 1.70 or more.156Al+18Ti+12Nb+11Mn+5V+328.125N+243.75C+12.5S≤12.5  (1)Ca/S≥4.0  (2)

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