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:
Dec. 24, 1991
Filed:
Jun. 21, 1990
Kohsaku Ushioda, Sagamihara, JP;
Osamu Akisue, Sagamihara, JP;
Naoki Yoshinaga, Sagamihara, JP;
Tomohisa Katayama, Sagamihara, JP;
Masakazu Oshimi, Sagamihara, JP;
Nippon Steel Corporation, Tokyo, JP;
Abstract
A process for producing a non-aging galvanized steel sheet having good formability in a continuous galvanizing production line, which comprises heating a low carbon, Al-killed cold rolled steel sheet at a temperature not lower than a recrystallizing temperature, reducing the surface of the steel sheet thus heated in a reducing atmosphere, cooling the steel sheet to a temperature (T.sub.E) ranging from 200.degree. to 350.degree. C. from a temperature not lower than 600.degree. C. at a cooling rate not less than 30.degree. C/s, holding the steel sheet at the temperature (T.sub.E) for 0 to less than 10 seconds, reheating the steel sheet to a temperature ranging from 430.degree. to 500.degree. C. at a heating rate not less than 10.degree. C/s, immersing the steel sheet into a molten zinc bath, cooling the steel sheet thus galvanized to a temperature not higher than 370.degree. C., and subjecting the steel sheet to an overaging treatment to a temperature range from 250.degree. to 320.degree. C. for not shorter than 40 seconds. A modified process according to the present invention further comprises reheating the galvanized steel sheet to a temperature raning from 480.degree. to 600.degree. C. at a heating rate not lower than 10.degree. C/s, and holding the sheet in this temperature range to perform alloying of the zinc coating layer with the steel substrate.