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:
Nov. 25, 2003
Filed:
Sep. 24, 2001
Nobuyuki Nakamura, Fukuyama, JP;
Takeshi Fujita, Fukuyama, JP;
Katsutoshi Ito, Fukuyama, JP;
Yasuyuki Takada, Fukuyama, JP;
NKK Corporation, Tokyo, JP;
Abstract
The present invention relates to a high carbon steel sheet having chemical composition specified by JIS G 4051 (Carbon steels for machine structural use), JIS G 4401 (Carbon tool steels) or JIS G 4802 (Cold-rolled steel strips for springs), wherein the ratio of number of carbides having a diameter of 0.6 &mgr;m or less with respect to all the carbides is 80% or more, more than 50 carbides having a diameter of 1.5 &mgr;m or larger exist in 2500 &mgr;m of observation field area of electron microscope, and the &Dgr;r is more than −0.15 to less than 0.15. The high carbon steel sheet of the invention is excellent in hardenability and toughness, and formable with a high dimensional precision.