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:
May. 27, 2003
Filed:
Nov. 14, 2000
Akitsugu Fujita, Nagasaki, JP;
Masatomo Kamada, Yokohama, JP;
Mitsubishi Heavy Industries, Ltd., Tokyo, JP;
Abstract
In CrMoV based heat resistant steels and tungsten-containing CrMoV based heat resistant steels, trace impurities, such as phosphorus, sulfur, copper, aluminum, arsenic, tin, and antimony are reduced lower than a specific level. Furthermore, alloy steels having increased creep strengths in a creep test on an unnotched test piece by addition of trace impurities such as cobalt, tantalum, nitrogen, boron, or the like is used. The production process therefor includes heating a turbine rotor member having the specific composition at a temperature between 980° C. and 1100° C. at a part corresponding to the high-pressure part thereof and at a temperature between 850° C. and 980° C. at a part corresponding to the low-pressure part thereof, and cooling the turbine rotor member at a cooling rate higher than an air impact cooling rate at the part corresponding to the high-pressure part thereof, and at a cooling rate no lower than an oil quenching rate at the part corresponding to the low-pressure part thereof. The rotor member has a creep rupture time in a creep test on a notched test piece of 10000 hours or longer.