Creep Crack Growth in P92 and P122 Alloy Steel Weldment

Abstract:

The structures connected by welding are fractured often in Heat Affected Zone (HAZ) when cracks grow under high-temperature and high-pressure conditions. In this study, the creep crack growth tests of P92 and P122 steels were performed and the creep fracture characteristics were evaluated. Degradation rate by cavities was investigated and the influence of degradation rate on crack growth rate was evaluated. Crack growth rate of new material was compared with that of the degraded material to confirm the influence of the degradation rate by cavities on the crack growth rate. From these results, the crack growth rates in welded joints were determined. The crack growth rate of the step test specimen was much faster than that of new material under the same test conditions of step temperature, while it was slower than that of new material under the same step loading conditions. It implies that crack growth rate of the welded specimen is faster when degradation rate by cavities is high even under the same temperature and stress conditions. HAZ and weld metal have faster cavity nucleation and growth rates than base metal. Therefore, the HAZ and weld metal specimens showed shorter crack initiation time and the initial crack growth rate (da/dt)c of the HAZ and weld metal was faster than the base metal. If (da/dt)c is fast, fracture life will be reduced.

• Periodical: Key Engineering Materials (Volumes 297-300)
• Pages: 446-451
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.297-300.446
• Online since: November 2005
• Authors: C.S. Jeong, Si Yon Bae, Byeong Soo Lim
• Keywords: Area Fraction of Void, Creep Crack Growth, Creep Rupture, Life Fraction, Micro-Cavity

References

[1] M. Tabuchi, T. Watanabe, K. Kubo, M. Matsui, J. Kinugawa and F. Abe: International Journal of Pressure Vessels and Piping 78 (2001), p.779.

DOI: 10.1016/s0308-0161(01)00090-4

[2] B.S. Lim and C.S. Jeong: Key Engineering Materials Vol. 261-263 (2004), p.1319.

[3] B. Dogan and B. Petrovski: International Journal of Pressure Vessels and Piping 78 (2001), p.795.

[4] N. Le Mat Hamata and I.A. Shibli: International Journal of Pressure Vessels and Piping 78 (2001), p.819.

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

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

[7] T. Yokobori and A.T. Yokobori Jr: International Journal of Pressure Vessels and Piping78 (2001), p.903.

[8] T.H. Hyde, W. Sun and A.A. Becker: International Journal of Pressure Vessels and Piping 78 (2001), p.765.