Creep Life Evaluation by Micro-Cavities

Abstract:

As the operation time of a power plant increases, the degradation and the cracks inside of the structure exposed to high temperature will increase gradually. Therefore, degradation rate, crack growth rate and fracture life of the structure can be evaluated according to the level of degradation and the growth of crack length. We performed creep rupture test and crack growth test with stress and temperature changes to evaluate the degradation rate, crack growth rate and fracture life. Degradation rate was evaluated using micro-cavities. The area fraction of the cavities increased with the increasing temperature and life fraction (t/tf). da/dt, the crack growth rate against Ct estimated from the relationship between load line displacement rate and cavity increase rate, was in good agreement with the result of da/dt vs Ct acquired from the test. It shows that the creep crack growth rate can be evaluated by the increase of cavity area fraction. It was also found that the predicted life calculated with the cavity growth rate was in good agreement with experimental results.

• Periodical: Key Engineering Materials (Volumes 297-300)
• Pages: 1858-1863
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.297-300.1858
• Online since: November 2005
• Authors: C.S. Jeong, Byeong Soo Lim
• Keywords: Area Fraction of Void, Creep Crack Growth, Creep Rupture, Life Fraction, Micro-Cavity

References

[1] S.B. Biner: Engineering Fracture Mechanics 69 (2002), p.923.

[2] B. Michel: Nuclear Engineering and Design 227 (2004), p.161.

[3] R.P. Wei, H. Liu and M. Gao: Acta Materialia 46 (1998), p.313.

[4] H.C. Furtado, I. Le May: Materials Characterization 36 (1996), p.175.

[5] C.S. Jeong and B.S. Lim: Key Engineering Materials 261 (2004), p.1319.

[6] H. Sato, K. Sawada, K. Maruyama and H. Oikawa: Materials Science and Engineering A319 (2001), p.746.

[7] I. Komura, T. Hirasawa, S. Nagai, J.I. Takabayashi and K. Naruse: Nuclear Engineering and Design 206 (2001), p.351.

DOI: 10.1016/s0029-5493(00)00421-0

[8] A. Saxena: Nonlinear Fracture Mechanics for Engineers (CRC Press, U.S. A 1998).

[9] C. Phaniraj, B.K. Choudhary, K. Bhanu Sankara Rao and B. Raj: Scripta Materialia 48 (2003), p.1313.

DOI: 10.1016/s1359-6462(03)00021-6