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. 23, 1994
Filed:
May. 06, 1993
Akira Yoshino, Osakasayama, JP;
Massaki Tahara, Takatsuki, JP;
Haruo Senbokuya, Tondabayashi, JP;
Kenzo Kitano, Kawachinagano, JP;
Teruo Minato, Hashimoto, JP;
Daidousanso Co., Ltd., Osaka, JP;
Abstract
An austenitic stainless steel screw having a nitride hard layer on its surface to prevent corrosion on parts of the screw such as a screw head which is in contact with the environment by removing a portion of the nitride hard layer to expose austenitic stainless steel base. By contrast, in the thread part and the like of the screw, the nitride hard layer is retained to improve the hardness and the tapping functions of the screw. In the method for manufacturing, the austenitic stainless steel screw is exposed to a fluorine-or fluoride-containing gas atmosphere prior to nitriding to form a fluoride film on its surface and then is nitrided in that state. Accordingly, the so formed nitride hard layer becomes uniform and deep to obtain an austenitic stainless steel screw having excellent surface properties.