Technical Note: Corrosion Fatigue Crack Growth of Forged Type 316NG Austenitic Stainless Steel in 325°C Water

Forged Type 316NG austenitic stainless steel is commonly used to fabricate primary coolant pipe in advanced pressurized water reactor systems, but it is subject to corrosion fatigue cracking in primary coolant environments. In this study, the fatigue crack growth of Type 316NG austenitic stainless steel in 325 degrees C water was investigated. The corrosion fatigue effect in 325 degrees C water was mainly correlated to the crack growth rate and load frequency. A maximum F-en (environment corrected factor) value up to 100 was observed at f = 0.005 Hz, Delta K = 13 MPa root m. The dissolved oxygen tended to have little influence on the fatigue crack growth. The crack path was deflected and branched. Most secondary cracks tended to be initiated from grain boundaries.