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:
Nov. 17, 2015
Filed:
May. 25, 2012
Shinya Teramoto, Tokyo, JP;
Hiromasa Takada, Tokyo, JP;
Manabu Kubota, Tokyo, JP;
Yoichi Taniguchi, Tokyo, JP;
Junichi Nakatsuka, Tokyo, JP;
Kazuhiro Fujimura, Tokyo, JP;
Satoshi Koganemaru, Tokyo, JP;
Shinya Teramoto, Tokyo, JP;
Hiromasa Takada, Tokyo, JP;
Manabu Kubota, Tokyo, JP;
Yoichi Taniguchi, Tokyo, JP;
Junichi Nakatsuka, Tokyo, JP;
Kazuhiro Fujimura, Tokyo, JP;
Satoshi Koganemaru, Tokyo, JP;
NIPPON STEEL AND SUMITOMO METAL CORPORATION, Tokyo, JP;
Abstract
The present invention provides a steel part for machine structural use whose fatigue strength and toughness are improved and a manufacturing method thereof. A steel part made of a steel containing, in mass %, C: 0.05 to 0.20%, Si: 0.10 to 1.00%, Mn: 0.75 to 3.00%, P: 0.001 to 0.050%, S: 0.001 to 0.200%, V: exceeding 0.20 to 0.25%, Cr: 0.01 to 1.00%, Al: 0.001 to 0.500%, and N: 0.0080 to 0.0200%, and a balance being composed of Fe and inevitable impurities, in which a steel structure contains a bainite structure having an area ratio of 95% or more, a bainite lath width is 5 μm or less, V carbide having an average grain diameter of not less than 4 nm nor more than 7 nm dispersedly exists in the bainite structure, and an area ratio of V carbide in the bainite structure is 0.18% or more.