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:
Jun. 04, 2024
Filed:
Feb. 23, 2015
Usui Kokusai Sangyo Kaisha, Ltd., Shizuoka, JP;
Nippon Steel & Sumitomo Metal Corporation, Tokyo, JP;
Tatsuya Masuda, Shizuoka, JP;
Tsugumi Yamazaki, Shizuoka, JP;
Taizo Makino, Tokyo, JP;
Katsunori Nagao, Tokyo, JP;
Tsutomu Okuyama, Tokyo, JP;
USUI CO., LTD., Shizuoka, JP;
NIPPON STEEL CORPORATION, Tokyo, JP;
Abstract
A steel pipe has a composition consisting, by mass percent, of, C: 0.12 to 0.27%, Si: 0.05 to 0.40%, Mn: 0.3 to 2.0%, Al: 0.005 to 0.060%, N: 0.0020 to 0.0080%, Ti: 0.005 to 0.015%, Nb: 0.015 to 0.045%, Cr 0 to 1.0%, Mo: 0 to 1.0%, Cu: 0 to 0.5%, Ni: 0 to 0.5%, V: 0 to 0.15%, and B: 0 to 0.005%, the balance being Fe and impurities. As impurities, contents are Ca: 0.001% or less, P: 0.02% or less, S: 0.01% or less, and O: 0.0040% or less. The micro-structure is tempered martensitic or tempered martensite and tempered bainite, in which a prior-austenite grain size number is 10.0 or more. Tensile strength is TS 800 MPa or higher. Critical internal pressure is [0.3'TS′a] or more, a=[(D/d)−1]/[0.776′(D/d)], D: pipe outer diameter (mm), d: pipe inner diameter (mm).