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:
Jul. 28, 2015
Filed:
Nov. 25, 2010
Kimihiro Nishimura, Chiyoda-ku, JP;
Nobuyuki Ishikawa, Fukuyama, JP;
Akihiko Tanizawa, Fukuyama, JP;
Hitoshi Sueyoshi, Fukuyama, JP;
Masayuki Horie, Fukuyama, JP;
Yasumitsu Kiyoto, Fukuyama, JP;
Kimihiro Nishimura, Chiyoda-ku, JP;
Nobuyuki Ishikawa, Fukuyama, JP;
Akihiko Tanizawa, Fukuyama, JP;
Hitoshi Sueyoshi, Fukuyama, JP;
Masayuki Horie, Fukuyama, JP;
Yasumitsu Kiyoto, Fukuyama, JP;
JFE Steel Corporation, Chiyoda-Ku, JP;
Abstract
Provided are a steel pipe for a linepipe with high compressive strength and a heavy wall thickness, and a method of manufacturing the same. Lowering of yield stress caused by a Bauschinger effect can be suppressed by optimizing the metal microstructure of a steel plate without requiring particular forming conditions in forming the steel pipe, and without requiring heat treatment after pipe making. A steel pipe has the composition which contains by mass % 0.03 to 0.10% C, 0.30% or less Si, 1.00 to 2.00% Mn, 0.015% or less P, 0.003% or less S, 0.080% or less Al, 0.005 to 0.035% Nb, 0.005 to 0.020% Ti, and Fe and unavoidable impurities as a balance. The steel pipe has metal microstructure where a fraction of bainite is 60% or more, a fraction of rolled ferrite is 5% or less, and a fraction of M-A constituent (MA) is 3% or less.