PSI - Issue 13

Yinghao Cui et al. / Procedia Structural Integrity 13 (2018) 1291–1296 Author name / Structural Integrity Procedia 00 (2018) 000 – 000

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Fig.5 Creep strain under wedging stress, external load and joint action

The creep strain under wedging stress, external load and joint action of wedging stress and external load is shown when crack length is 0.2 mm is shown in Fig.5. Fig.5 indicates that the creep strain produced by wedging stress is gradually less than that the creep strain produced by the external load. The biggest creep strain also appears in the 0° position.

Fig.6 Creep strain under wedging stress, external load and joint action

The creep strain under wedging stress, external load and joint action of wedging stress and external load when crack length a=2 mm is shown in Fig.6, which indicates that the creep strain produced by wedging stress is much less than the creep strain produced by the external load. Therefore, the contribution of wedging stress to the creep strain is very small, and only has no influence on the creep strain at the crack tip. 5. Conclusion 1) The creep strain close to the crack tip is an appropriate parameter in the investigating of the effect of mechanical factor on crack growth rate, and accordingly the crack tip creep strain increasing will induce EAC crack growth rate increase. 2) The wedging stress produced by the formation of oxide film is the main factor affecting creep strain during the SCC full life cycle, while the working load and residual stress gradually becomes the main mechanical parameter determining creep strain at crack tip. 3) In the initial stage the crack propagation rate is very slow. This is same for the majority of the whole life. It will expand rapidly under the combined effect of residual stress and working load if there is an initial crack in the structural material. In this case the structure will result in failure and will be destroyed. Acknowledgements This work is financially supported by the Natural Science Foundation of China (51475362, 11502195). References [1] Zinkle S J, Was G S. Materials challenges in nuclear energy[J]. Acta Materialia, 2013, 61(3): 735-758. [2] O. K. Chopa, H. M. Chung, and etc. Current research on environmental assisted cracking in light water reactor environments, Nuclear Engineering and Design, 194, 205-223, 1999. [3] Andresen P L, Karen G, Lawrence N J. Stress Corrosion Cracking of Sensitized Type 304 Stainless Steel in 288C Water: A Five Laboratory