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. 16, 2010
Filed:
May. 23, 2003
Mitsuru Yoshizawa, Amagasaki, JP;
Kunio Kondo, Sanda, JP;
Masaaki Igarashi, Sanda, JP;
Yuichi Komizo, Nishinomiya, JP;
Mitsuru Yoshizawa, Amagasaki, JP;
Kunio Kondo, Sanda, JP;
Masaaki Igarashi, Sanda, JP;
Yuichi Komizo, Nishinomiya, JP;
Sumitomo Metal Industries, Ltd., Osaka, JP;
Abstract
A martensitic stainless steel provided includes C: 0.01-0.1% and Cr: 9-15%, and the retained austenite phase has a thickness not more than 100 nm in such a manner that the X-ray integral intensities of 111γ and 110α satisfy the following formula (a):0.005≦111γ/(111γ+110α)≦0.05  (a)Such a metal structure can be obtained by the following procedure: the steel is heated at a temperature of the Acpoint or more, and then cooled from 800° C. to 400° C. at a cooling rate of not less than 0.08° C./sec and further cooled down to 150° C. at a cooling rate of not more than 1° C./sec. The martensitic stainless steel according to the present invention has a relatively high carbon content and a greater toughness in spite of a high mechanical strength, and further exhibits an excellent corrosion resistance, so that it is particularly effective as the material for constructing a deep oil well.