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A B S T R A C T Fatigue crack growth was investigated in Haynes 230, a nickel-based superalloy. Anisotropic stress intensity factors were calculated with a least squares algorithm using the displacements 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 crystallographic orientation. Finally, a finite element model was adopted to examine plasticity around the crack tip. Results were compared with the experimentally observed strains.Keywords effective stress intensity factor range; fatigue crack growth; mixed-mode propagation; plastic zone; single crystal nickel-based alloy; single crystal plasticity. N O M E N C L A T U R Ea ij = Elastic constants A = Rigid body rotation B u = Horizontal rigid body translation B v = Vertical rigid body translation C = Paris law coefficient g = Slip system strength h 0 = Slip system initial hardening modulus h aβ = Single crystal hardening matrix K I = Mode I stress intensity factor K II = Mode II stress intensity factor n = Paris law exponent q = Latent hardening coefficient r = Radial distance from crack tip R = Load ratio S = Yield stress in the shear direction (Hill's criterion) t = ratio between ΔK II and ΔK I T = T-stress term u = Horizontal displacements v = Vertical displacements X, Y, Z = Yield stress in the principal directions (Hill's criterion) z = Rate sensitivity exponent α = Energy release rate ratio factor γ = Shear strain ΔK I = Mode I stress intensity factor range ΔK II = Mode II stress intensity factor range ΔK I,eff = Mode I effective stress intensity factor range ΔK II,eff = Mode II effective stress intensity factor range ΔK tot = Combined stress intensity factor range Correspondence: S. Rabbolini.

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