Evaluation of multiple stress corrosion crack interactions by in-situ Digital Image Correlation

Digital Image Correlation (DIC), Acoustic Emission and Electrochemical Noise measurements were applied to study the growth of multiple intergranular cracks as a colony on an Alloy 600 in a tetrathionate solution. Cracks exceeding 55 mu m in length and 0.45 mu m in opening were successfully detected by DIC. Moreover, crack population was classified into initiating, active and dormant cracks, active population being the larger one. The emergence and intensification of interactions produced a modification on the colony growth behavior. They range from a mostly surface crack propagation (in the absence of interactions), to in depth propagation predominantly governed by crack shielding.