The anisotropic fatigue short crack initiation and propagation
behaviours of a directionally solidified (DS) superalloy CM247LC at room
temperature
Abstract
The effects of mechanical and microstructural anisotropy on short
fatigue crack initiation and propagation behaviours of a directionally
superalloy have been studied. An unusual result was found where the
fatigue lives of specimens with grains longitudinally aligned along the
loading direction fail at lower lifetimes than the specimens with
transversely loaded grains when the applied stress is close to the yield
stress. This is mainly attributed to the lower Young’s modulus of the
longitudinal specimen, which induces more local plastic strain (at
stress concentration features) leading to earlier crack initiation and
faster crack propagation under the applied test stress.