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. 01, 1994
Filed:
Jun. 07, 1993
Saiji Matsuoka, Chiba, JP;
Hidetaka Kawabe, Chiba, JP;
Eiko Yasuhara, Chiba, JP;
Kei Sakata, Chiba, JP;
Toshiyuki Kato, Chiba, JP;
Kawasaki Steel Corporation, Kobe, JP;
Abstract
In a method of producing a high-strength cold-rolled steel sheet excelling in deep drawability, a steel material is used which consists of: a basic composition including 0.01% or less of C, 0.1 to 2.0% of Si, 0.5 to 3.0% of Mn, 0.02 to 0.2% of P, 0.05% or less of S, 0.03 to 0.2% of Al, 0.01% or less of N, 0.001 to 0.2% of Nb, and 0.0001 to 0.008% of B in such a way that the respective contents of C, Nb, Al, N, Si, Mn and P satisfy the following formulae: 5.ltoreq.Nb/C.ltoreq.30, 10.ltoreq.Al/N.ltoreq.80, and 16.ltoreq.(3.times.Si/28+200 .times.P/31)/(Mn/55).ltoreq.40; Fe remnant; and inevitable impurities, the method including the steps of: performing rolling on the steel material with a total reduction of 50% or more and 95% or less while effecting lubrication thereon in a temperature range of not higher than the Ar.sub.3 transformation temperature and not lower than 500.degree. C.; performing a hot-rolled sheet recrystallization treatment on the steel material by a coiling or annealing process; performing cold rolling on the steel material with a reduction of 50 to 95%; and then effecting recrystallization annealing on the steel material in a temperature range of 700 .degree. to 950.degree. C.