Life prediction under tension of titanium alloys that develop an oxygenated brittle case during use

► We model the life prediction of alpha + beta titanium alloys. ► Experiments include tensile tests after exposure to air at temperature. ► Minimum stress to initiate crack and saturation spacing modeled and validated. ► Oxygen diffusion model used to predict degradation depth. ► A life prediction framework for arbitrary time–temperature–oxygen history suggested. A simple model was used to predict the tendency of an (α + β) titanium alloy to crack under tension after exposure to air at temperature. The model was experimentally validated for minimum stress to crack and saturation crack spacing. A diffusion model for oxygen ingress as a function of time, temperature and oxygen partial pressure is outlined; together with the surface cracking model and empirical crack growth models, this enables the framework for a life prediction tool for arbitrary time–temperature–environment history.