Study On Microstructural Evolution Of Lamellar Structure And Globularization Kinetics Of Titanium Alloy

Studying the manufacturing technology of the dual property compressor disk is an effective way to improve the property of advanced engine components under appalling conditions. It is an important component of the strategy for future development in many developed countries. Strain controllable forging is one of the important means to achieve the dual property compressor disk. And the globularization mechanism of lamellar microstructure is core technology of strain controllable forging. Therefore, studying the globularization mechanism of lamellar microstructure in Ti-17 alloy has important theoretical and practical value for full playing to the performance potential of materials and improving engine performance. In this paper, isothermal compression test, optical metallography, SEM and TEM were used to analysis the laws of a lamellae separating and the globularization mechanism of lamellar microstructure in Ti-17 alloy during deformation. A brief introduction to the project and its main achievement are as follows:Isothermal compression test revealed the laws about deformation temperature, deformation degree and strain rate affect the flow stress of Ti-17 alloy during high temperature deformation. Based on Zener-Hollomon parameters, a hyperbolic sine constitutive equation with simple form and fit high accuracy was established in Ti-17 alloy.A discontinuous yielding phenomenon was observed in Ti-17 alloy with lamellar microstructure. This phenomenon can not be reasonably explained by conventional static theory (locking and unlocking). It has been generally accepted that this phenomenon was associated with the sudden generation of new mobile dislocation from grain boundary sources.The stress curves at the faster strain rates exhibited significant flow softening feature. The main reasons of flow softening are the effect of rising temperature and the globularization of lamellar microstructure and lamellae kinking.The curves of globularization kinetics during hot working of Ti-17 alloy were established show the laws of the globularization process attribute to the thermodynamic parameters of deformation degree, strain rate and deformation temperature. It was discovered that deformation degree is the primary factor of...