| A new alpha-beta high temperature and high strength titanium alloy was compared in this paper, and its heat treatment processings and phase transformation behaviors were carried out.The different microstructures and phases at various solution temperatures and cooling rates, and the effect of varied aging temperatures and aging terms for microstructure and phase were investigated by hardness-meter, X-ray diffraction, optical microscopy and scanning electron microscopy. By optimized heat treatments, the anneal treatments, duple and triple heat treatments were carried out for Ti650-2 alloy and Ti650-1 alloy, respectively. The mechanical properties were evaluated including tensile properties and impact toughness at room temperature and 650°C. Later, the relationship among heat treatment processings and microstructure and mechanical properties of Ti650 titanium alloy was studied.The result was showed: the Ti650 titanium alloy had high hardening potential.α′′,α′,α+βphases were respectively obtained by water cooling ,oil cooling, air cooling and furnace cooling under treated at 995°C. The content of prime alpha of Ti650 titanium alloy was increased, and the microstructure translated from Widmanstaten structure, prime alpha+ Widmanstaten structure to prime alpha+translated beta microstructure by reducing solution temperature.In Ti650-1 titanium alloy, the translated mode wasα′′→α′→α+β. The nose temperature of (TTT) curve ofα′′/(α+β) transformation was about 750°C. The ageing temperature was higher, and the hardness of the Ti650-1 titanium alloy was lower. The hardness was better adjusted and controlled by aging at 600°C.Compared with near alpha titanium alloy, the tensile strength at 650°C was improved by adding beta stabilized elements, Mo and W. Furthermore, it existed a excellent value. The nominal Mo level was 2.5wt%, the nominal W was 1.4wt% for our paper.
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