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:
May. 19, 2015
Filed:
Mar. 25, 2010
Yusuke Nakagawa, Fukuyama, JP;
Masaki Tada, Fukuyama, JP;
Katsumi Kojima, Fukuyama, JP;
Hiroki Iwasa, Kawasaki, JP;
Yusuke Nakagawa, Fukuyama, JP;
Masaki Tada, Fukuyama, JP;
Katsumi Kojima, Fukuyama, JP;
Hiroki Iwasa, Kawasaki, JP;
JFE Steel Corporation, Tokyo, JP;
Abstract
A component composition contains, by % by mass, 0.0016 to 0.01% of C, 0.05 to 0.60% of Mn, and 0.020 to 0.080% of Nb so that the C and Nb contents satisfy the expression, 0.4≦(Nb/C)×(12/93)≦2.5. In addition, the amount of Nb-based precipitates is 20 to 500 ppm by mass, the average grain diameter of the Nb-based precipitates is 10 to 100 nm, and the average crystal grain diameter of ferrite is 6 to 10 μm. Nb is added to ultra-low-carbon steel used as a base, and the amount and grain diameter of the Nb-based precipitates are controlled to optimize the pinning effect. Grain refinement of ferrite is achieved by specifying the Mn amount, thereby achieving softening and excellent resistance to surface roughness of steel.