Key Takeaways & Executive Findings
- •• Established a quantitative DRX kinetics model for Ti-10V-2Fe-3Al alloy, linking DRX grain size and volume fraction to abnormal coarse grain (ACG) formation during solid solution. • Identified critical DRX criteria (dDRX ≤ 2.60 μm, 72.5% ≤ XDRX ≤ 87.9%) that predict ACG occurrence, showing that both excessive and insufficient DRX suppress ACG. • Developed a finite element simulation platform with a coarse grain criterion subroutine to visually predict macroscopic ACG distribution in die forging, validated by experiments. • Demonstrated that deformation temperature and strain rate significantly influence DRX and ACG, providing process windows to avoid ACG defects in aerospace components.
Abstract
After the hot deformation sample of Ti-10V-2Fe-3Al alloy was treated by solid solution in the α+β two-phase region, the coarse β grains that often appeared in the β single phase region were observed in the local region, indicating that the abnormal grain growth occurred in the local microstructural region, and the macrostructure also showed abnormally coarse grains (ACGs). The dynamic recrystallization (DRX) behavior of Ti-10V-2Fe-3Al titanium alloy was systematically investigated through hot compression tests on the Gleeble-3800 system. The DRX model of β grains was established, and the quantitative correlation between DRX characteristics and the appearance of ACG was clarified. Based on these results, a numerical simulation platform was developed to realize the visual prediction of ACG distribution. The results show that the increase of deformation temperature and the decrease of strain rate both contribute to a significant increase in the grain size (dDRX) and volume fraction (XDRX) of DRXed grains. However, the proper XDRX and smaller dDRX at low deformation temperature and high strain rate make the macro and microstructure show ACGs after solid solution. Interestingly, if the DRX degree is excessive or insufficient, ACGs cannot be produced, indicating that ACGs are solid solution products based on the appropriate DRX degree. According to the flow curves and statistical results of microstructure, the quantitative model of DRX kinetics and DRX grain size model were constructed, and the quantitative criterion model that is related to the formation of ACG with grain size (dDRX) and volume fraction (XDRX) of DRXed grains as the key parameters was established, i. e., dDRX£2.60 μm, 72.5%£XDRX£87.9%. By integrating the subroutine of coarse grain criterion, the isothermal compression process of cylindrical samples and the actual die forging process of H-shaped parts were simulated by DEFORM-3D software of finite element (FE), respectively, and the visual prediction of the distribution of macroscopic ACGs was realized. There is a good consistency between the tested results and the simulated results, indicating a strong correlation between macroscopic ACGs and microscopic DRX.
1. Introduction
Ti-10V-2Fe-3Al alloy, a typical nearly β-type titanium alloy, has an excellent combination of strength, fracture toughness and corrosion resistance, whereby it has been widely used to manufacture various kinds of aviation components [1, 2] (e.g., landing gear [3], rotor systems [4].) with complex shape through die-forging process at high temperature. For this kind of aerospace die forgings, due to the complex structure and shape, it is easy to lead to uneven deformation in different forging parts during the forming process. This often leads to the problem of microstructure uniformity in forging manufacturing [5, 6], resulting in low-magnification defects, which in turn affects mechanical properties [7].
Moreover, Ti-10V-2Fe-3Al titanium alloy is prone to defects of ACG during solid solution [8], which leads to the problem of microstructure uniformity in the manufacture of forging part and to the differences in mechanical properties of Ti-10V-2Fe-3Al alloy. In order to avoid the influence of the ACG defects, it is even necessary to remove localized regions with ACG defects, which greatly reduces the production yield of titanium alloy die forgings.
Recently, several literatures reported the strong correlation between DRX behavior and ACG formation in Ti alloys. DAVIS et al [9] systematically proposed dominate process parameters that control the level of β recrystallization, specifically focusing on final grain size and mic...
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ZHANG Yu-sen, CHEN Lei, GAO Xiao-peng, GUO Cong-de, CAI Xing-zhou, JIN Miao, MA Xiao-cong (2025). Prediction of macroscopic abnormally coarse grain during solid solution of Ti-10V-2Fe-3Al alloy based on dynamic recrystallization kinetics. Journal of Central South University. https://doi.org/10.1007/s11771-025-6126-9
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Frequently Asked Questions
What is the main objective of this study?
The study aims to predict the occurrence of macroscopic abnormally coarse grains (ACGs) during solid solution treatment of Ti-10V-2Fe-3Al alloy by establishing a quantitative relationship between dynamic recrystallization (DRX) characteristics and ACG formation, and to develop a numerical simulation platform for visual prediction.
How was the DRX behavior of Ti-10V-2Fe-3Al alloy investigated?
Hot compression tests were conducted on a Gleeble-3800 system to systematically investigate the DRX behavior. The DRX model of β grains was established, and the quantitative correlation between DRX characteristics and ACG appearance was clarified.
What are the critical DRX parameters for ACG formation?
The quantitative criterion model indicates that ACGs form when the DRX grain size (dDRX) is ≤ 2.60 μm and the DRX volume fraction (XDRX) is between 72.5% and 87.9%. Both excessive and insufficient DRX degrees suppress ACG formation.
How was the visual prediction of ACG distribution achieved?
A subroutine incorporating the coarse grain criterion was integrated into DEFORM-3D finite element software. Simulations of isothermal compression and actual die forging of H-shaped parts were performed, and the predicted ACG distribution showed good consistency with experimental results.
What is the significance of this research for industry?
The findings provide a predictive tool to avoid ACG defects in titanium alloy die forgings, thereby improving production yield and ensuring uniform mechanical properties in aerospace components.
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