Fatigue crack growth in Haynes 230 single crystals: An analysis with digital image correlation

Fatigue crack growth was investigated in Haynes 230, a nickel-based superalloy. Aniso- tropic stress intensity factors were calculated with a least squares algorithm using the dis- placements obtained from digital image correlation. Crack opening/sliding levels were measured by analysing the relative displacement of crack flanks. Reversed crack tip plastic zones were calculated adopting an anisotropic yield criterion. The strains measured in the reversed plastic zone by digital image correlation showed a dependence on crystallo- graphic orientation. Finally, a finite element model was adopted to examine plasticity around the crack tip. Results were compared with the experimentally observed strains.