| Ti-1300 alloy is a super high strength titanium alloy which developed by Northwest Institute For Non-ferrous Metal Research. This alloy has great forgeability and high hardenability, and optimum matching of plasticity and ductility under 1300MPa conditions. Ti-1300 alloy has complex phase transformation during solution and aging, its microstructure and propertity are sensitive to the heat treating regime. Because Ti-1300 alloy is newly, so we have little research on it, this will limit its application on aerospace industry.In order to offer some experiences of its applications, the microstructure and properties of Ti-1300 alloy treated by normal solution and aging, heated from room temperature after solution and tin bath after solution are studied in this paper. The phase transformation of Ti-1300 alloy during heat treatment is observed by means of XRD, OM, SEM and TEM .The results show that the microstructure of Ti-1300 alloy is single and equiaxedβphase after solution above the transformation point, the grain size reduced with the temperature decreased, and the granular and needleαphase was observed inβmatrix after solution above the transformation point.Ti-1300 alloy owned optimal strength and plastic by aging at 570°C after solution at 790℃, because the interaction of phase transformation driving force and solute atoms diffusion velocity made moreαphase was observed in the matrix, andαphase refining the structure.Theωtransformation occurred when Ti-1300 alloy was heated to 400℃from room temperature after soluted at 850℃for 1 hour. When the alloy was heated to 500℃, most βphase changed toωphase, there is still a fewα. When it kept worm for 4 hours later,ωphase transformed intoαphase. Theωphase made the strength of the alloy rise rapidly, but plasticity decreased. So theωphase must be avoided when aging treatment in order to get the best properties, therefore, the aging treatment temperature should be chose between 500℃～600℃and time should be chose for 4 hours.The strength and plastic was increased by fine grain strengthening after Ti-1300 alloy was soluted at 850℃for 1 hour. Duringβ→αphase transformation, it was observed thatαphase nucleated at grain boundary firstly, because grain boundary had big shear resistance and many defects, it can produce energy difference and ensureαphase appearance.The aging response character of Ti-1300 alloy after tin bath is more quickly than that of Ti-B19 and Ti-B20, moreover, the aging response rate is higher than BETA-C and Ti-15-3 of metastableβtitanium alloys in business application.
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