Fatigue Crack Growth Behavior of SS316LN Steel with Varying Temperature and Frequencies

SS 316LN is extensively employed in sodium cooled fast reactors as structural materials for different high-temperature components. These components experience different kinds of damage mechanisms such as low- and high-cycle fatigue, creep, ratcheting, creep and creep-fatigue. Hence it is very essential to predict the life and assess the integrity of these components. To perform the same, information related to initiation and growth behavior of crack under the influence of cyclic loading are necessary. The fatigue crack growth behavior of SS 316LN was investigated at frequencies 0.75, 15 and 75 Hz in the temperature range of 623-823 K. The result showed increasing growth rate with decreasing frequencies. The influence of high temperatures in crack growth behavior was also evident. The influence of different mechanisms such as dynamic strain aging and slip character were also investigated. The fractographic features of fractured surfaces were discussed as well.