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. 01, 2019
Filed:
Mar. 16, 2012
Daisuke Maeda, Tokyo, JP;
Osamu Kawano, Tokyo, JP;
Kazuya Ootsuka, Tokyo, JP;
NIPPON STEEL CORPORATION, Tokyo, JP;
Abstract
The issue of the present invention is to provide a hot-rolled steel sheet with excellent press formability and method for producing the steel sheet, wherein the steel sheet has not only hole expandability but also stretch flanging workability by not assessing hole expandability for stretch flanging as conventional but an actual phenomena of side-bend elongation. To solve the issue, it is confirmed that the steel sheet are excellent in hole expandability and stretch flanging workability, wherein the steel sheet with a certain content of C, Si and Mn is characterized in that, in a metallic structure of said steel sheet, the area fraction of ferrite is 70% or more, the area fraction of bainite is 30% or less, the area fraction of either one or both of martensite and retained austenite is 2% or less, and with regard to respective average intervals (L, Land L), average diameters (D, Dand D) and number densities of a cementite, an inclusion and either one or both of martensite and retained austenite (n, nand n), a void formation/connection index L defined by formula 1 is 11.5 or more: