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. 27, 2017
Filed:
May. 14, 2010
Hitoshi Hatano, Hyogo, JP;
Kotaro Toyotake, Fukuoka, JP;
Hitoshi Hatano, Hyogo, JP;
Kotaro Toyotake, Fukuoka, JP;
Kobe Steel, Ltd., Kobe-shi, JP;
SHINKO METAL PRODUCTS CO., LTD., Kitakyushu-shi, JP;
NHK SPRING CO., LTD., Yokohama-shi, JP;
Abstract
A hollow seamless pipe for a high-strength spring with reduced occurrence of decarburization in the inner and outer peripheral surfaces, hardened surface layers in the inner and outer peripheral surfaces during quenching, and sufficient fatigue strength is provided. The hollow seamless pipe contains a steel material, which includes 0.2 to 0.7 mass % of C, 0.5 to 3 mass % of Si, 0.1 to 2 mass % of Mn, more than 0 and 0.1 mass % or less of Al, more than 0 and 0.02 mass % or less of P, more than 0 and 0.02 mass % or less of S, and more than 0 and 0.02 mass % or less of N. The C content in the inner and outer peripheral surfaces is 0.10 mass % or more. A thickness of a whole decarburized layer in each of the inner peripheral surface and the outer peripheral surface is 200 μm or less.