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. 27, 1990
Filed:
Dec. 22, 1989
Saiji Matsuoka, China, JP;
Susumu Satoh, Chiba, JP;
Toshiyuki Katoh, Chiba, JP;
Hideo Abe, Chiba, JP;
Ikuo Yarita, Chiba, JP;
Kawasaki Steel Corporation, Kobe, JP;
Abstract
A method of manufacturing a steel sheet having excellent deep-drawability. A steel blank is rolled into a steel sheet having a predetermined thickness. The steel contains C: not more than 0.008 wt %, Si: not more than 0.5 wt %, Mn: not more than 1.0 wt %, P: not more than 0.15 wt %, S: not more than 0.02 wt %, Al: 0.010 to 0.10 wt %, N: not more than 0.008 wt %, and at least one element selected from the group consisting of Ti and Nb which is contained in an amount satisfying the relationship of 1.2 (C/12+N/14).ltoreq.(Ti/48+Nb/93). In at least one pass, rolling is conducted within a temperatures range lower than the Ar3 transformation point but not lower than 500.degree. C., in such a manner that the roll radius R (mm) and the blank thickness t (mm) before rolling by rolls satisfy the relationships of R.ltoreq.200 and R.sup.2 .times..sqroot.t.ltoreq.100000, and the total rolling reduction at temperature lower than the Ar3 transformation point is not lower than 60%. The hot-rolled steel sheet possesses a high level of Lankford value, and is free from cold-working embrittlement. The method may include the step of obtaining, after the rolling, pickling, annealing and hot dip galvanizing under certain conditions, a surface-treated steel sheet having excellent deep-drawability.