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

Abstract:

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.

• Periodical: Key Engineering Materials (Volumes 297-300)
• Pages: 1470-1476
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.297-300.1470
• Online since: November 2005
• Authors: Takayuki Sugimoto, Shinichi Komazaki, Toshihei Misawa
• Keywords: Creep Properties, CrMoV Casting Steel, DBTT, Degradation, SP Creep Test, SP Test

References

[1] J.M. Baik, J. Kameda and O. Buck: Scripta Metallurgica 17 (1983), pp.1443-1447.

[2] J. Kameda and O. Buck: Materials Science and Engineering 83 (1986), pp.29-38.

[3] T. Misawa, T. Adachi, M. Saito and Y. Hamaguchi: Journal of Nuclear Materials 150 (1987), pp.194-202.

[4] T. Matsushita, M.L. Saucedo-Munoz, Y.H. Joo and T. Shoji: Proc. of the KSME/JSME Joint Conference, Fracture and Strength '90, KSME/JSME, Seoul (1990), pp.259-264.

[5] Y.H. Joo, T. Hashida and H. Takahashi: Journal of Testing and Evaluation 20 (1992), pp.6-14.

[6] X. Mao, T. Shoji and H. Takahashi: Journal of Testing and Evaluation 15 (1987), pp.30-37.

[7] X. Mao and H. Takahashi: Journal of Nuclear Materials 150 (1987), pp.42-52.

[8] T. Misawa, S. Nagata, N. Aoki, J. Ishizaki and Y. Hamaguchi: Journal of Nuclear Materials 169 (1989), pp.225-232.

[9] J.D. Parker, J.D. James: Developments in a Progressing Technology, ASME, PVP-Vol. 279 (1994), pp.167-172.

[10] S. Tettamanti and R. Crudeli: Proc. of an Internaional Symposium on Case Histories on Integrity and Failures in Industry, Milan, Italy (1999), pp.895-905.

[11] S. Komazaki, T. Hashida, T. Shoji and K. Suzuki: Journal of Testing and Evaluation 28 (2000), pp.249-256.

[12] M.L. Saucedo-Munoz, S. Komazaki, T. Takahashi, T. Hashida and T. Shoji: Journal of Materials Research 17 (2002), p.1945-(1953).

[13] H. Takahashi, T. Shoji, X. Mao, Y. Hamaguchi, T. Misawa, M. Sito, T. Oku, T. Kodaira, K. Hukaya, H. Nishi and M. Suzuki: JAERI-memo 62-193 (1987).

[14] N.S. Cheruvu: Metall. Trans. A, 20A (1989), pp.87-97.

[15] T. Matsushita, M.L. Saucedo-Munoz, M. Yotsutsuji, T. Shoji and H. Takahashi: Trans. Jpn. Soc. Mech. Eng. Series A 55 (1989), pp.1619-1622.

[16] P.C. Zhai, T. Hashida, S. Komazaki and Q.J. Zhang: Journal of Testing and Evaluation, 32 (2004), pp.298-303.