Characterization of seawater hygrothermal conditioning effects on the properties of titanium-based fiber-metal laminates for marine applications

The mechanical properties and corrosion behavior of the pure titanium TA2, carbon fiber/epoxy composite (CF/E composite), and titanium-carbon fiber/epoxy fiber-metal laminate (Ti FML) have been investigated after hygrothermal conditioning in seawater at 70 °C for marine applications. The results showed that the percentage reduction in the mechanical properties of the Ti FML was lower, compared to the CF/E composite, due to the shielding effect of outer TA2 layers against the water absorption. Unconditioned Ti FML specimens showed composite prepreg failure, whereas conditioned specimens exhibited delamination at the metal/composite prepreg interface as the primary failure mode. Plasticizing and swelling of the epoxy resin due to the combined effect of elevated temperature and water absorption, caused the generation of residual stresses that resulted in delamination at the metal/composite prepreg and fiber/resin interfaces. The TA2 foil showed negligible crevice corrosion on the surface because of the formation of the stable oxide film.