Abstract
The Gleeble-3800 thermal simulation machine was used to perform hot compression experiments on a new type of β alloy, Ti-6Mo-5V-3Al-2Fe (wt.%), at temperatures of 700–900 °C, strain rates of 5 × 10−1 to 5 × 10−4 s−1, and total strain of 0.7. Transmission and EBSD techniques were used to observe the microstructure. The results show that the deformation activation energy of the alloy was 356.719 KJ/mol, and dynamic recrystallization occurred during the hot deformation. The higher the deformation temperature was, the more obvious the dislocations that occurred and the more sufficient the dynamic recrystallization that occurred, but the effect of strain rate was the opposite. When the deformation temperature was higher than the phase transition point, the recrystallized grains clearly grew up. The calculated strain rate sensitivity index of the alloy was 0.14–0.29. The constitutive equation of hot deformation of Ti-6Mo-5V-3Al-2Fe alloy was established by using the Arrhenius hyperbolic sine equation. The dynamic DMM hot working diagram with the strain of 0.7 was constructed. The relatively good hot working area of the alloy was determined to be the deformation temperature of 700–720 °C and 0.0041–0.0005 s−1.
Highlights
Titanium alloy has been widely used in aerospace and other fields because of its advantages such as high density and low strength [1,2,3,4]
One of the reasons for this phenomenon is that the β grains are too coarse [8]. β grain size in metastable β titanium alloy is subject to internal softening mechanisms such as dynamic recovery and dynamic recrystallization during hot working
It was found that dynamic recrystallization is the hot deformation mechanism of TB6 alloy, and the main nucleation mechanism of new recrystallized grains is arch bending nucleation
Summary
Titanium alloy has been widely used in aerospace and other fields because of its advantages such as high density and low strength [1,2,3,4]. Β grain size in metastable β titanium alloy is subject to internal softening mechanisms such as dynamic recovery and dynamic recrystallization during hot working. Aneta [12] systematically studied the Ti-3Al-8V-6Cr-4Zr-4Mo alloy with a hot working diagram She established the hot working diagram using a dynamic material model (DMM) to accurately describe the steady-state and unsteady-state regions of the alloy during high-temperature deformation. As a new type of β titanium alloy, its hot deformation behavior during hot working is still unclear. The dynamic recrystallization behavior of Ti-6Mo-5V-3Al-2Fe alloy under different states was analyzed in combination with the characteristics of the actual stress–true strain curve during the hot compression process, and the constitutive equation and hot working diagram were established. The deformation mechanism and the rheological instability region during the hot deformation of the alloy were analyzed
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