Ti-6Al-4V welded joint exhibits different fatigue characteristics.
The fatigue crack propagates along α/β boundaries in the BM.
The fatigue crack propagates through α phases and martensite laths in the HAZ.
The fatigue crack propagates along α/β boundaries and martensite laths in the FZ.
Fatigue crack growth rate is fastest in the HAZ, less in the FZ, slowest in the BM.