Experimental investigation on dwell-fatigue property of Ti-6Al-4V ELI used in deep-sea manned cabin

The deep-sea manned cabin endures dwell-fatigue loading process during service. The high strength titanium alloy Ti-6Al-4V ELI adopted for the manufacture manned cabin is of creep nature in the room temperature. So the dwell-fatigue property of this material should be evaluated for service life estimation. This paper presents the experimental research results on dwell-fatigue property of Ti-6Al-4V ELI. The strain accumulations under different loading conditions are reported. Results show that the strain accumulation behavior of the material under dwell-fatigue loading conditions are very similar to that under the condition of normal creep with three stages; and the increase in total strain with respect to number of cycles was much more pronounced for specimen at higher stress level, while the dwell time will affect strain accumulation when it is plotted versus cycles while strain accumulation tends to be similar in the abscissa of time for different dwell time under test. Based on the results, a dwell-fatigue life curve is derived based on the analysis, which can be applied in the material evaluation and service life estimation of the manned cabin.