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:
Jan. 25, 2005
Filed:
Aug. 23, 2002
Yukio Miyata, Handa, JP;
Mitsuo Kimura, Handa, JP;
Takaaki Toyooka, Handa, JP;
JFE Steel Corporation, , JP;
Abstract
A method of producing a high-strength high-toughness martensitic stainless steel seamless pipe which includes heating a martensitic stainless steel raw material to an austenitic range and subjecting the raw material to piercing and elongating to form an original pipe. The original pipe is cooled to form a structure substantially composed of martensite in the original pipe. The original pipe is reheated to a temperature in the dual-phase range between the Atransformation point and the Atransformation point, and is subjected to finishing rolling at an initial rolling temperature T (° C.) between the Atransformation point and the Atransformation point. The original pipe is then cooled to form a processed pipe. The processed pipe is tempered at a temperature below the Atransformation point. The reduction in area R in the finishing rolling step may be in the range of 10% to 90%, and the initial rolling temperature T and the reduction in area R may satisfy the relationship 800≦T−0.625R≦850.