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. 03, 2003
Filed:
Sep. 21, 1998
Applicant:
Inventors:
Tohru Hayashi, Ibaraki, JP;
Shiro Torizuka, Ibaraki, JP;
Kaneaki Tsuzaki, Ibaraki, JP;
Kotobu Nagai, Ibaraki, JP;
Osamu Umezawa, Ibaraki, JP;
Assignee:
National Research Institute for Metals, Ibaraki, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
C21D 7/00 ;
U.S. Cl.
CPC ...
C21D 7/00 ;
Abstract
A fine ferrite-based steel is disclosed, wherein at least 60% of the ferrite grain boundary is a large angle grain boundary of at least 15°, and the mean ferrite grain size is not more than 2.5 &mgr;m. The fine ferrite-based steel of the invention has a high strength and a long fatigue life.