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:
Oct. 19, 2010
Filed:
Nov. 27, 2006
Makoto Okonogi, Muroran, JP;
Kenichiro Naito, Tokyo, JP;
Kohki Mizuno, Wako, JP;
Hideki Matsuda, Wako, JP;
Seiji Kobayashi, Wako, JP;
Makoto Okonogi, Muroran, JP;
Kenichiro Naito, Tokyo, JP;
Kohki Mizuno, Wako, JP;
Hideki Matsuda, Wako, JP;
Seiji Kobayashi, Wako, JP;
Nippon Steel Corporation, Tokyo, JP;
Honda Motor Co., Ltd., Tokyo, JP;
Abstract
The present invention provides a method of production of a steel soft nitrided machine part comprising: preparing a steel material containing, by mass %, C: 0.15-0.30%, Si: 0.03-1.00%, Mn: 0.20-1.5%, S: 0.04-0.06%, Cr: 0.01-0.5%, Mo: 0.40-1.5%, Nb: 0.005-0.05%, Ti: 0.005-0.03%, V: 0.2-0.4%, Ni: 0.05-1.5%, N: 0.002-0.0048%, a balance of Fe and unavoidable impurities, limiting P to 0.02% or less, limiting Ceq. (equation (1)) to 0.65-0.85, controlling DI (equation (2)) to 80-155, log Kp (equation (3)) to 2.5-8, and Si and Mn contents according to equation (4), heating the steel material to 1150-1280° C., hot forging the steel material to the shape of the part, cooling the steel material at a 0.5-1.5° C/sec cooling rate to obtain a hot forged part having a micrometallic structure with more than 50% of bainite, machining the hot forged part, and soft nitriding the machined hot forged part at 550-650° C. for 30 minutes or more.