Fatigue behavior of the nickel-base superalloy Waspaloy™ under proportional biaxial-planar loading at high temperature

The uniaxial and biaxial fatigue behavior of the forged nickel-base superalloy Waspaloy™ was investigated at 400 °C and 650 °C. Biaxial-planar tests were carried out at two different strain modes in order to study the influence of the multiaxial stress state on the fatigue life. The comparison of uniaxial, and biaxial lifetimes to literature data at both temperatures shows a good agreement. The equivalent strain hypothesis according to von Mises correlates the fatigue lives of the different stress states within the scatterband of two. Crack initiation, crack growth and the macroscopic crack path were studied by scanning electron microscopy. Transgranular and intergranular fracture at 400 °C and 650 °C were found.