Abstract
In order to improve the understanding of the dynamic recrystallization (DRX) behaviors of TA15 titanium alloy (Ti-6Al-2Zr-1Mo-1V), a series of experiments were conducted on a TMTS thermal simulator at temperatures of 1173 K, 1203 K, 1223 K, and 1273 K with the strain rates of 0.005 s−1, 0.05 s−1, 0.5 s−1, and 1 s−1. By the regression analysis for conventional hyperbolic sine equation, the activation energy of DRX inα+βtwo-phase region isQS=588.7 Kg/moland inβregion isQD=225.8 Kg/mol, and a dimensionless parameter controlling the stored energy was determined asZ/A=ε˙exp(588.7×103)/RT/6.69×1026inα+βtwo-phase region and asZ/A=ε˙exp(225.8×103)/RT/5.13×1011inβregion. The DRX behaviors of TA15 titanium alloy were proposed on the strength of the experiment results. Finally, the theoretical prediction results of DRX volume fraction were shown to be in agreement with experimental observations.
Highlights
The near α-type titanium alloy, Ti-6Al-2Zr-1Mo-1V (TA15 titanium alloy), with high specific strength, good creep resistance and corrosion resistance, good thermal stability, and excellent welding performance, has been widely used in aerospace industry [1,2,3]
The true stress-strain curves displayed that the work-hardening and softening mechanism vary with strain rate and deformation temperature, which showed that the flow behavior is the conclusion of the dynamic recrystallization and dynamic recovery against work-hardening in isothermal hot compression tests of TA15 titanium alloy
The stress decreases with the increase of deformation temperature at the same strain rate and with the decrease of strain rate under the same deformation temperature. It indicates that the flow stress of TA15 titanium alloy is extremely sensitive to strain rates and deformation temperature
Summary
The near α-type titanium alloy, Ti-6Al-2Zr-1Mo-1V (TA15 titanium alloy), with high specific strength, good creep resistance and corrosion resistance, good thermal stability, and excellent welding performance, has been widely used in aerospace industry [1,2,3]. There are several models that have been reported to express the flow stress and the evolution of dynamic recrystallization of alloy. The constitutive model proposed by Sellars and Tegart has been widely used for describing flow behaviors of the metal alloys [5, 6]. The DRX kinetics model was proposed based on Avrami function to study the dynamic recrystallization for metal alloy [9, 10]. The Sellars-Tegart model [11, 12] and the JMAK equation are widely used to express peak stress and the dynamic recrystallization evolution [8]. The constitutive equation and DRX kinetic model are obtained to characterize the deformation behavior in the isothermal compression. The theoretical prediction results of DRX volume fraction were shown to be in agreement with experimental observations
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