The use of titanium alloys in the automotive, aerospace and naval industry is always increasing, due to their favorable strength to mass ratio and to their excellent fatigue performances. However, recent experiments on Ti-6Al-4V notched specimens in a methanol solution have shown a dramatic degradation of the alloy fatigue endurance limits, with a reduction of the maximum applied stress of up to 50%, at R=0.1. The aim of the present work is the investigation of the mechanical and chemical driving forces involved in the Ti-6Al-4V stress-corrosion mechanism in methanol. Experimental quasi-static tests on Ti-6Al-4V notched flat dog-bone specimens, with gage area submersed in methanol solution at different concentrations, were performed. Results in aggressive environment were compared with quasi-static tests in inert environment and with fatigue tests in methanol, in order to identify and decouple the chemical and mechanical effects. Numerical models of the specimens were developed, in order to evaluate the stress concentration factor Kt. Finally the fracture surfaces were observed by SEM in order to study in deep the fatigue mechanisms and the effect of the corrosive environment.
