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. 26, 2010
Filed:
Nov. 04, 2004
Teruki Hayashida, Oita, JP;
Masahiro Ohara, Oita, JP;
Teruki Hayashida, Oita, JP;
Masahiro Ohara, Oita, JP;
Nippon Steel Corporation, Tokyo, JP;
Abstract
The present invention provides a high strength hot rolled steel sheet raised in Si content, wherein a conversion coating can be formed homogeneously over the entire surface of the steel sheet, no new step is added in the production of the steel sheet, and quality control is also facilitated, comprising, by mass %, C: 0.03 to 0.15%, Si: 0.8 to 3.0%, Mn: 0.5 to 3.0%, P: 0.07% or less, S: 0.01% or less, Al: 0.015 to 0.1%, N: 0.001 to 0.008%, and, if necessary, having Ti, Nb, etc. added, the oxides on the steel sheet surface having an Si concentration of 3.5% or less and an Mn concentration of 3.5% or less. Preferably, the average roughness Ra is 3.0 μm or less and the pitting due to pickling is an average of 5 or less in 10 μn side squares. The scale after the hot rolling is washed off by dipping the sheet in a solution having an HCl concentration of 7 to 15% and an Fe ion concentration of 4 to 12% at a solution temperature of 80 to 98° C. for 40 sec or more.