Influence of texture and microstructure on corrosion-fatigue in Ti-6Al-4V

Microstructure and texture in the (α + β) titanium alloy Ti-6Al-4V were systematically varied by thermomechanical processing to obtain material suitable for investigating corrosion fatigue in aqueous salt solution. While equiaxed material exhibits higher strength and ductility, coarse lamellar microstructures have superior crack growth characteristics. For equiaxed microstructures, texture is seen to have a dramatic influence on the stress corrosion cracking susceptibility and in turn on corrosion-fatigue. In lamellar microstructures, texture can evidently not be controlled so as to influence on the fracture mechanics properties, but can be used to influence strength. Thus the deliberate control of texture in lamellar microstructures offers a possibility to combine the desirable properties of both conditions. A well-behaved dependence of the relative stress corrosion cracking sensitivity on the basal pole density parallel to the loading axis is observed.