Fatigue Mechanism of Domestic 316LN Stainless Steel in Simulated AP1000 First-Loop Water Environment

Abstract:

Fatigue fracture surfaces and crack morphologies of 316LN stainless steel that test in a simulated AP1000 first-loop water and air environment were investigated by SEM, LSCM and EBSD. The results showed that, the fatigue crack initiated at persistent slip band, impurities and grain boundary, and then propagated in a trans-granular manner with typical fatigue striations. Characteristics of corrosion fatigue, such as brittle fatigue striation, rhomboid corrosion product and the trace of corrosions were found on the fracture surface of first-loop water environment specimen. The strain on first-loop water environment specimen is unevenly distributed surrounding the crack, and the gradient is not obvious, while that on air environment ones is evenly distributed , and the distribution gradient is associated with the distance of crack from . The fatigue crack propagation was accelerated in the first-loop water environment, and the EAC mechanism is most likely to be HIC.

• Periodical: Materials Science Forum (Volume 913)
• Pages: 247-253
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.913.247
• Online since: February 2018
• Authors: Wei Hua Zhong, Zhen Feng Tong*, Zheng Wang, Jin Xu Li, Wen Yang
• Keywords: 316LN, Corrosion Fatigue, Fatigue, Fatigue Mechanism, Primary Coolant Pipe

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