| High performance aviation engines usually work at severe working environment of elevated temperature, high pressure and high loading, etc, which is very harsh for the materials. In recent years, more and more attention has been paid on the research of high temperature titanium alloys used at 600°C all over the world. These alloys are mainly used as components of high ratio aviation engine, e.g. compressor disks, blades and casings.A special kind of near-alpha titanium alloy named after Ti600 used at 600°C was developed in China. The alloy has favorite comprehensive properties of tensile strength, elevated temperature creep resistance and so on. So studying high temperature deformation behavior of the alloy is very beneficial for hot process of Ti600 alloy.The hot deformation behavior, evolution of the microstructure and softening mechanisms of Ti-600 alloy have been studied with the aids of OM and TEM conducted on thermal simulator testing machine. The processing maps of Ti600 alloy was established by dynamic materials model and the high temperature deformation characteristics have been analyzed using processing map in detail. Conclusions can be drawn as follows:(1) The test discovered the influence of hot deformation parameters on flow stress of the alloy. The results indicated that Ti600 alloy is sensitive to the variety of temperature and strain rate, and the flow curves exhibited a peak stress followed by flow softening, and the flow softening behavior is more obvious with the decrease of deformation temperature. At higher strain rate, typically 10s-1, discontinuously yielding followed by flow oscillations was observed in (3 phase region. The phenomenon can be explained by dynamic theory. It has been generally accepted that this phenomenon was associated with the sudden generation of new mobile dislocation from grain boundary sources.(2) The test discovered the influence of hot deformation parameters on microstructure evolution of the alloy. Deformation in α+β phase region, lamellar structures globularization is main deformation dynamic. With the increment of deformation temperature, the lamellar a structures globularization is more quickly and more uniformity. The strain rates have great influence on the shape of the lamellar structure. With the increment of strain rate, the lamellar a structures is heavily... |
