The effect of aging time on microstructure and mechanical properties of Ti-5Mo-5V-6Cr-3Al alloy tube prepared by cold rolled for high pressure gas cylinder was investigated in this paper. The results show that α phase size and phase content of cold rolling tube increased rapidly in 1 hours at 560℃

and the tensile strength firstly increased and then decreased because which was affected by the size and content of α precipitates and dislocations and deformation twins

furthermore

plastic increased rapidly only owing to α phase size and phase content. Alpha precipitates grew slower and α phase content increased slower in 1- 4 hours

and the tensile strength firstly increased and then decreased because which was only affected by α phase size and phase content

meanwhile

plasticity continued to rise to the peak. Although α precipitates size and phase content most slowly increased in 4- 24 hours

but both of the tensile strength and plasticity decreased because of the coarsening α phase

in other words

over aging occurred.