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:
Aug. 19, 2014
Filed:
Dec. 13, 2011
Syunichi Ootsuka, Tokyo, JP;
Yoshitaka Nishiyama, Tokyo, JP;
Tadashi Kawakami, Tokyo, JP;
Nippon Steel & Sumitomo Metal Corporation, Tokyo, JP;
Abstract
Provided is a production method including: heating a workpiece at a temperature higher than an Atransformation point in a carburizing atmosphere; slowly cooling the workpiece at not more than 70° C./Hr down to a temperature T satisfying Formula (1) while maintaining the carburizing atmosphere: A−20≧T(° C.)≧300° C. . . . (1); and cooling the workpiece in an oxidizing atmosphere. According to this method, it is possible to efficiently produce a high-carbon chromium bearing steel whose depth of the recarburized layer or the overcarburized layer is within a range from 0 to 0.2 mm, having less machining allowance, and excellent in machinability, using a steel tube after hot tube-making.