Secondary orientation effects on the low cycle fatigue behaviors of rectangular‐sectional Ni‐based single crystal superalloys at medium and high temperatures

Abstract

Turbine blades made of Ni‐based single crystal superalloys (NBSXs) have long‐strip shaped cross sections and rectangular‐sectional structures, where the secondary orientation produces potential effects even the primary orientation is fixed at [001]. Low cycle fatigue behaviors between [010] and [110] transversely oriented rectangular‐sectional NBSX specimens were compared. Obvious differences existed under 600°C but disappeared under 850°C, with the deformation mechanism and fracture mode transitions. Secondary orientation effects on stress asymmetry and fatigue life cannot be described by the conventional LCP model and critical plane method but were well explained by dislocation path length‐dependent back‐stress model and A.N. May's random slip model.