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:
Feb. 21, 1978
Filed:
Oct. 20, 1976
Masakatsu Ueno, Kitakyushu, JA;
Osamu Kato, Kitakyushu, JA;
Nobuyuki Kawauchi, Shiki, JA;
Kametaro Itoh, Kitakyushu, JA;
Nippon Steel Corporation, Tokyo, JA;
Abstract
A molten steel, which may optionally contain boron to increase hardenability is poured into ingot molds, bloomed and primary hot worked to a mother tube of intermediate cross-section. Before being cooled down to below about 800.degree. C, the mother tube is reheated to about 930.degree. C, scale from the outside surface thereof is removed, and it is secondary hot worked to a pipe of final dimensions with a reduction, measured in terms of equivalent strain as expressed by the following formula, of not less than .epsilon. = 0.02 for the removal of scale from the inside surface of the pipe. It is then directly quenched to produce a finished seamless steel pipe having far better shape at a higher heat efficiency than in the conventional process. Better toughness is effected when the degree of secondary hot work is not smaller than .epsilon. = 0.20.