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:
Feb. 07, 2012
Filed:
Apr. 04, 2009
Taishi Fujishiro, Tokyo, JP;
Shinya Sakamoto, Tokyo, JP;
Takuya Hara, Tokyo, JP;
Hitoshi Asahi, Tokyo, JP;
Taishi Fujishiro, Tokyo, JP;
Shinya Sakamoto, Tokyo, JP;
Takuya Hara, Tokyo, JP;
Hitoshi Asahi, Tokyo, JP;
Nippon Steel Corporation, Tokyo, JP;
Abstract
The present invention provides high strength steel plate with excellent low temperature toughness, high strength steel pipe using this as a base metal, and methods of production of the same. The steel plate of the present invention contains Mo: 0.05 to 1.00% and B: 0.0003 to 0.0100%, has a Ceq of 0.30 to 0.53, has a Pcm of 0.10 to 0.20, and has a metal structure which has an area percentage of polygonal ferrite of 20 to 90% and has a balance of a hard phase comprised of one or both of bainite and martensite. To obtain this steel plate, strain-introducing rolling is performed with a start temperature of not more than Ar+60° C., an end temperature of Aror more, and a reduction ratio of 1.5 or more, then the plate is air-cooled and then acceleratedly cooled from Ar−100° C. to Ar−10° C. in temperature by 10° C./s or more.