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. 29, 1991
Filed:
Mar. 29, 1990
Yoshihiro Okamura, Tokai, JP;
Seinosuke Yano, Tokai, JP;
Ryota Yamaba, Tokai, JP;
Hidetaka Chiba, Tokai, JP;
Nippon Steel Corporation, , JP;
Abstract
A method of high tension steel having superior weldability and low temperature toughness, comprises the steps of preparing a steel billet having a composition consisting, by weight, of 0.02 to 0.05% C, 0.02 to 0.5% Si, 0.4 to 1.5% Mn, 0.5 to 4.0% Ni, 0.20 to 1.5% Mo, 0.005 to 0.03% Ti, 0.01 to 0.08% Al, not more than 0.0002% B, 0.5 to 2.0% Cu, not more than 0.01% N, and the balance Fe and incidental impurities; heating said steel billet to a temperature of 900.degree. C. to 1000.degree. C.; hot-rolling the heated steel billet first at a rolling reduction of 30 to 70% in a temperature range in which austenite recrystallizes and then at a rolling reduction of 20 to 60% in another temperature range in which austenite does not recrystallize; hardening the hot-rolled billet by water-cooling from a temperature not lower than the Ar.sub.3 transformation point and terminating the cooling at a temperature not higher than 250.degree. C.; and tempering the hardened billet at a temperature which is not higher than the Ac.sub.1 transformation point.