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:
Apr. 27, 1999
Filed:
Mar. 11, 1998
Masayuki Hashimura, Muroran, JP;
Masato Yanase, Muroran, JP;
Taisuke Nishimura, Wako, JP;
Takashi Otowa, Wako, JP;
Hiroshi Yarita, Tokyo, JP;
Ikuo Ochiai, Tokyo, JP;
Toshio Ozone, Nagoya, JP;
Masaaki Mikura, Nagoya, JP;
Nippon Steel Corporation, Tokyo, JP;
Honda Giken Kogyo Kabushiki Kaisha, Tokyo, JP;
Chuo Hatsujo Kabushiki Kaisha, Aichi, JP;
Abstract
The present invention provides, at low cost, a valve spring steel having a tensile strength as high as 210 to 240 kgf/mm.sup.2 after oil tempering. The high strength spring steel comprises, based on weight, 0.65 to 0.85% of C, 1.90 to 2.40% of Si, 0.50 to 1.00% of Mn, 0.70 to 1.30% of Cr, 0.10 to 0.30% of Mo, 0.20 to 0.50% of V, 0.01 to 0.04% of Nb and the balance Fe and unavoidable impurities and is subjected to heating at temperature of 1,050 to 1,250.degree. C. and then to rolling so that carbides in the steel have a size of up to 0.15 .mu.m in terms of equivalent circle. A valve spring having a tensile strength as high as 210 to 240 kgf/mm.sup.2 after oil tempering and stabilized quality can be produced while the material cost is greatly reduced by decreasing costly alloying components as much as possible.