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.:
Date of Patent:
Oct. 19, 2010
Filed:
Jan. 25, 2008
Yuji Arai, Amagasaki, JP;
Kunio Kondo, Sanda, JP;
Nobuyuki Hisamune, Kinokawa, JP;
Sumitomo Metal Industries, Ltd., Osaka, JP;
Abstract
The present invention relates to the following seamless steel pipes excellent in strength, toughness and weldability, particularly suitable for submarine flow lines, and a manufacturing method thereof. An as-quenched seamless steel pipe having a chemical composition consisting of, by mass%, C: 0.03 to 0.08%, Mn: 0.3 to 2.5%, Al: 0.001 to 0.10%, Cr: 0.02 to 1.0%, Ni: 0.02 to 1.0%, Mo: 0.02 to 0.8%, Ti: 0.004 to 0.010%, N: 0.002 to 0.008%, Ca: 0.0005 to 0.005%, and the balance Fe and impurities, with not more than 0.25% of Si, not more than 0.05% of P, not more than 0.005% of S, less than 0.005% Nb, and less than 0.0003% of B as the impurities, and having a microstructure consisting of not more than 20 volume% of polygonal ferrite, not more than 10 volume% of a mixed microstructure of martensite and retained austenite, and balance bainite. B can be 0.0003 to 0.001%. Mg and/or REM can be contained. The manufacturing method is characterized by the cooling rate during quenching.