The fatigue crack growth of the nickel-based superalloy Haynes 230 was investigated at
room temperature and 900 °C using digital image correlation (DIC). As expected, the crack
growth rates at high temperature were much faster than at room temperature. However,
the crack closure levels, which were determined using digital image correlation analysis
techniques, were found to be similar for the two cases studied. DIC strain fields and the
corresponding plastic zone sizes were compared between the two cases. From these strain
fields, the slip irreversibility, the difference between forward and reversed strains at the crack
tip, was quantitatively measured. The high temperature case had an order of magnitude
higher amount of slip irreversibility. Slip irreversibilitymeasurements were determined to be
an effectivemethod to compare fatigue crack growth of cases with differing temperatures.