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:
Apr. 15, 2014
Filed:
Sep. 20, 2011
Keiichi Kondo, Wakayama, JP;
Toshiharu Abe, Osaka, JP;
Kunio Kondo, Sanda, JP;
Yuichi Yano, Wakayama, JP;
Yuji Arai, Amagasaki, JP;
Keiichi Kondo, Wakayama, JP;
Toshiharu Abe, Osaka, JP;
Kunio Kondo, Sanda, JP;
Yuichi Yano, Wakayama, JP;
Yuji Arai, Amagasaki, JP;
Nippon Steel & Sumitomo Metal Corporation, Tokyo, JP;
Abstract
A method for suppressing shock and storage cracking when manufacturing seamless steel pipes comprises hot piercing and hot rolling a billet consisting of, by mass percent controlled amounts of C, Si, Mn, Cr, Mo, Ti, and Al, with the balance being Fe and impurities of Ni, P, S, N, and O also in controlled amounts. Further heat treatment is performed, wherein a hot rolled steel pipe is direct quenched from a temperature of not lower than the Artransformation point and the pipe is then subjected to heat treatment at a temperature of not lower than 450° C. and not higher than the Actransformation point in heat treatment equipment for performing direct quenching. The steel pipe subjected to the heat treatment is reheated, quenched from a temperature of not lower than the Actransformation point, and tempered at a temperature of not higher than the Actransformation point.