| The rapid development of the aerospace industry has led to the development and application of high-strength and high-toughness titanium alloys.Ti55531 titanium alloy is a new high strength and high thoughness titanium alloy.Compared with the earlier development high-strength and high-thoughness titanium alloy Ti-1023,the alloy will not produce obvious composition segregation,and has good hardenability and wide processing range.The studies of hot deformation and microstructure evolution of Ti55531 titanium alloy are important for theoretical and practical significance to guide the manufacturing process of Aeronautical die forging porducts,to tailor the microstructure and to optimize the hot working process.In this paper,the research object was Ti55531 titanium alloy,high-temperature compression test was conducted by using Gleeble-3800 thermal test machine.And the flow curves were obtained under the conditions of deformation temperature of730900°C and strain rate of 0.00110s-1.The influence of the deformation parameter on the flow curves was studied.Based on the thermal compression test data and the classical Arrhenius equation,the constitutive equation of Ti55531 titanium alloy was established in the two phase region.It was verified that it can be accurately used to predict the stress-strain relationship of Ti55531 titanium alloy in the two phase region.In the experimental conditions,the microstructure evolution of Ti55531 titanium alloy during hot deformation was studied.When the deformation was in single-phase zone,the influence of deformation parameters on the?grains and the?substructure was analyzed,and the model of dynamic recrystallization fraction were established.When the deformation was in two-phase zone,the influence of the deformation parameter on the?-phase content was mainly analyzed.According to the dynamic material model theory and Prasad instability criterion,the thermal processing map of Ti55531 titanium alloy at strain of 0.3,0.6 and 0.9 was established respectively.And the appropriate deformation parameter range of the alloy was obtained.The microstructure corresponding to different areas in the thermal processing map was analyzed,and the mechanism for the material instability was discussed. |
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