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. 10, 1998
Filed:
Dec. 21, 1995
Yasuhiko Tanaka, Muroran, JP;
Yasumi Ikeda, Muroran, JP;
Tsukasa Azuma, Muroran, JP;
Masayuki Yamada, Yokohama, JP;
Yoichi Tsuda, Yokohama, JP;
The Japan Steel Works, Ltd., Tokyo, JP;
Kabushiki Kaisha Toshiba, Kanagawa, JP;
Abstract
A rotor forging composed of Cr--Mo--V type alloy based on iron is normalizing-treated at a temperature of from 1000 to 1150.degree. C., the temperature is maintained at 650.degree.-750.degree. C. on the way of cooling the temperature from the normalizing-treating temperature to pearlite transform the microstructure of the rotor forging, the portions of the rotor forging corresponding to a high pressure or middle pressure portion are quenched at 940.degree.-1020.degree. C. and the portion corresponding to the low pressure portion is quenched at 850.degree.-940.degree. C. after the heat treatment is carried out at 920.degree.-950.degree. C. once or more times, and the rotor forging is subjected to tempering at 550.degree.-700.degree. C. once or more times. A high creep strength at the high and middle pressure portions can be obtained and, at the same time, the toughness at the low pressure portion is drastically enhanced.