The fatigue crack propagation resistance of Ti–6Al–4V under aqueous saline environments

Abstract Fatigue crack propagation rates are characterised for the titanium alloy Ti 6/4 in atmospheric air and under complete immersion in 3.5% salt solution. The alloy is assessed in three microstructural forms: mill annealed, bimodal and fully transformed lamellar. Through the employment of a corner crack specimen geometry containing a part through crack with a maximum length of 2.5 mm, the lamellar variant demonstrates microstructurally sensitive growth for cracks shorter than 1 mm. The growth rate response is highly dependent on both environment and mean stress. Relative to this, both the mill annealed and bimodal microstructures are shown to be insensitive to salt solution conditions.