Abstract
The flow behavior and microstructure change of the Ti-55511 alloy are investigated by thermal compression experiments with stepped strain rates. The phase transformation features, the dynamic recrystallization (DRX) behavior of the β matrix, the dynamic spheroidization mechanism of the lamellar α phase and the evolution of the β sub-grain size are quantitatively analyzed. A unified constitutive model is constructed to characterize the hot deformation features of the Ti-55511 alloy. In the established model, the work hardening effect is taken into account by involving the coupled effects of the equiaxed and lamellar α phases, as well as β substructures. The dynamic softening mechanisms including the dynamic recovery (DRV), DRX and dynamic spheroidization mechanisms are also considered. The material parameters are optimized by the multi-objective algorithm in the MATLAB toolbox. The consistency between the predicted and experimental data indicates that the developed unified model can accurately describe the flow features and microstructure evolution of the hot compressed Ti-55511 at stepped strain rates.
Highlights
Due to the advantages of excellent strength and high elastic modulus/fracture toughness/hardness, the near β titanium alloys are widely used in some key aviation components such as aircraft landing gear, wing connection fasteners, etc. [1,2,3]
The plastic flow behavior and microstructure evolution of a Ti-55511 alloy are researched by hot compression experiments with time-varying strain rates
Both DDRX and CDRX of the β phase can be observed during the hot compression with stepped strain rates
Summary
Due to the advantages of excellent strength and high elastic modulus/fracture toughness/hardness, the near β titanium alloys are widely used in some key aviation components such as aircraft landing gear, wing connection fasteners, etc. [1,2,3]. Due to the advantages of excellent strength and high elastic modulus/fracture toughness/hardness, the near β titanium alloys are widely used in some key aviation components such as aircraft landing gear, wing connection fasteners, etc. As a typical near β titanium alloy, the Ti-5Al-5Mo-5V-1Cr-1Fe (Ti-55511) alloy with a good balance of strength and breaking tenacity is widely applied in manufacturing the important aviation components. The thermomechanical process of Ti-55511 alloy has been investigated by isothermal compression experiments, in which the deformation parameters (temperature, strain rate) are constant [6,7,8]. It is significant to investigate the hot deformation behavior and microstructure evolution of the Ti-55511 alloy by dynamic compression experiments with time-varying strain rates
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