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:
Mar. 10, 2015
Filed:
Feb. 04, 2011
Taishi Fujishiro, Tokyo, JP;
Takuya Hara, Tokyo, JP;
Yoshio Terada, Tokyo, JP;
Shinya Sakamoto, Tokyo, JP;
Hitoshi Asahi, Tokyo, JP;
Taishi Fujishiro, Tokyo, JP;
Takuya Hara, Tokyo, JP;
Yoshio Terada, Tokyo, JP;
Shinya Sakamoto, Tokyo, JP;
Hitoshi Asahi, Tokyo, JP;
Nippon Steel & Sumitomo Metal Corporation, Tokyo, JP;
Abstract
A high-strength welded steel pipe is obtained by welding a seam weld portion of a steel plate that are formed in a pipe shape. In the high-strength welded steel pipe, a base metal of the steel plate includes, by mass %, C: 0.010% to 0.080%, Si: 0.01% to 0.50%, Mn: 0.50% to 2.00%, S: 0.0001% to 0.0050%, Ti: 0.003% to 0.030%, Mo: 0.05% to 1.00%, B: 0.0003% to 0.0100%, O: 0.0001% to 0.0080%, N: 0.006% to 0.0118%, P: limited to 0.050% or less, Al: limited to 0.008% or less, and the balance of Fe and inevitable impurities, Ceq is 0.30 to 0.53, Pcm is 0.10 to 0.20, [N]−[Ti]/3.4 is less than 0.003, the average grain size of the prior γ grains in heat affected zones in the steel plate is 250 μm or less, and the prior γ grains include bainite and intragranular bainite.