Comparative experiment of high-temperature crack propagation behaviors for four kinds of typical titanium alloys

Fatigue experiments were carried out on four kinds of titanium alloys of TC18, TC21, TC4-DT and Ti-6Al-4V/ELI subjecting to constant amplitude loading at two temperatures of 25℃ and 250℃, so as to determine the fatigue crack propagation behaviors. Fatigue crack propagation behaviors at different temperatures were analyzed and compared with each other, and the interaction mechanisms between high-temperature and fatigue load were deduced from fractographical studies by using scanning election microscope (SEM) analysis. Results showed that there were great differences between crack propagation rate behaviors of different titanium alloys at different temperatures. Fatigue surfaces at high temperature had more secondary cracks and showed more significant light yellow than those at room temperature. Fatigue crack propagation of titanium alloy was governed by the interaction effect between high-temperature and fatigue load due to the crack closure and oxidation effects.