(a) (b)
Fig. 11. Longitudinal section of the specimen subjected to IPD-TMF
cycling with mechanical strain amplitude 6×10−3 to
fracture; (a) SEM image, (b) EBSD image.
Introduction of the tensile dwell to the loading cycle led also to the
formation of the internal damage referred to as creep deterioration.
Internal cracks developed during IPD-TMF cycling are documented on the
longitudinal section of a specimen in Fig. 12. EBSD image in Fig. 12b
reveals that the internal cracks follow the grain boundaries. The
internal damage may significantly influence the growth of the dominant
fatigue crack due to interaction of this crack with the internal cracks
which were nucleated close to the crack tip. The joining of the dominant
crack with internal cracks accelerates the crack growth.