Evaluation of DBTT and Creep Properties of Aged Main Valve Casing by Using Small Punch Specimens

Abstract:

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Both the change in DBTT and the degradation of creep properties of the aged CrMoV cast steel which had been actually used as a main steam valve were evaluated from the conventional SP test and the SP creep (SP-C) test using by SP test specimens. The CVN DBTTs of the virgin and aged steels were estimated to be 280 and 369 K by the conventional SP test, respectively. This increase in DBTT after the long-term service exposure was considered to be caused by carbide-induced embrittlement due to coarse carbides. The SP-C test results revealed that the creep rupture strength of the aged steel was inferior to that of the virgin steel. The ratio, F / s , between the load of the SP-C test (F) and the stress of the uniaxial test ( s) was determined to be 2.4 for the same value of the Larson-Miller parameter in the creep rupture data. This linear relationship enables us to convert the results of the SP-C test into those corresponding to a conventional uniaxial creep test. Consequently, the SP testing method is expected to be appropriate tool for the determination of material deterioration and, in turn, the assessment of remaining-life of high-temperature components.

Info:

Periodical:

Key Engineering Materials (Volumes 297-300)

Edited by:

Young-Jin Kim, Dong-Ho Bae and Yun-Jae Kim

Pages:

1470-1476

DOI:

10.4028/www.scientific.net/KEM.297-300.1470

Citation:

T. Sugimoto et al., "Evaluation of DBTT and Creep Properties of Aged Main Valve Casing by Using Small Punch Specimens ", Key Engineering Materials, Vols. 297-300, pp. 1470-1476, 2005

Online since:

November 2005

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Price:

$35.00

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