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:
Sep. 27, 2005
Filed:
Sep. 20, 2002
Nobuaki Takahashi, Kashima, JP;
Akio Yamamoto, Kashima, JP;
Tomoaki Ikeda, Kashima, JP;
Tetsuya Fukuba, Kashima, JP;
Nobuaki Takahashi, Kashima, JP;
Akio Yamamoto, Kashima, JP;
Tomoaki Ikeda, Kashima, JP;
Tetsuya Fukuba, Kashima, JP;
Sumitomo Metal Industries, Ltd., Osaka, JP;
Abstract
The high yield ratio problem intrinsic in high-strength steel pipes is solved and a method of producing a steel pipe, while securing the pipe roundness is provided. A steel pipe produced from a steel plate by forming and welding is subjected to 0.3 to 1.2% of expansion and then to 0.1 to 1.0% of reduction. The steel pipe produced by this method has a structure in which martensite and/or bainite accounts for more than 80% as expressed in terms of area percentage, and has a yield strength of not lower than 551 MPa and a yield ratio of not higher than 93%. The pipe reduction is desirably carried out at a lower work ratio as compared with the pipe expansion.