Effect of cyclic oxidation on the tensile behavior of directionally solidified CM-247LC Ni-based superalloy at 870 °C

The effect of cyclic oxidation exposure at 1100 °C in air on the tensile properties of directionally solidified Ni-based superalloy CM-247LC has been studied. The residual machining stresses present in the tensile samples induced the formation of a recrystallization zone at the surface during oxidation exposure. Additionally, a γ′ precipitate-free zone also formed at the surface of the tensile specimens. The tensile properties of the alloy, including YS, UTS and ductility, were greatly degraded because of the oxidation exposure. The deterioration in the properties can be ascribed to the combined effect of the above mentioned surface damages and the microstructural degradation in terms of the coarsening of primary γ′ precipitates of the substrate during the high temperature exposure.