Small fatigue crack growth in aluminium alloy EN-AW 6082/T6

The kinetics of small fatigue crack growth at room temperature was measured using light microscopy observation of the cracks in a shallow notch of a cylindrical specimen. Symmetrical tension–compression cycling was adopted. The growth of the crack was measured within the range of half surface crack length from ∼10 μm up to ∼2 mm. A linear dependence between the crack growth rate and the crack length, observed in case of steels, was confirmed to be valid in the aluminium 6082/T6 alloy, too. The crack growth coefficient kg increases with plastic strain amplitude; this dependence is well described by a power law. The fatigue life prediction based on the crack growth measurements is compared with the Manson-Coffin law.