Failure Behavior of Sensitized SUS304 Stainless Steel with Small Surface Pre-Crack under Constant Load Condition in Simulated BWR Environment

Small surface intergranular cracks similar to those detected in the heat affected zone of the welded components of primary water recirculation loop for boiling water reactor (BWR) were introduced on the surface of sensitized SUS304 stainless steel by using a fretting fatigue technique, where multiple parallel small surface cracks in the localized fretting slip region were nucleated. Constant load tests at various initial stress intensity factors (Ki) were then carried out in 288°C, 7.3MPa pure water, which is the operating condition for BWR, to investigate failure behavior of this material under constant load condition. From the results, it was speculated that the KISCC for small surface crack was lower than 4.7MPa·m1/2, which was significantly low compared to that of long crack (10-20 MPa·m1/2).

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