Key Takeaways & Executive Findings
- •• Prolonging pouring time in vacuum centrifugal casting transforms coarse columnar grains into refined equiaxed grains in Ti-46Al alloy tubes. • Optimal pouring time of 6 s at 1,600 °C and 800 r·min-1 yields tensile strengths of 650 MPa at room temperature and 705 MPa at 800 °C. • ProCAST simulations effectively predict solidification behavior and microstructure evolution under high gravity conditions. • The study provides a viable method for producing high-performance TiAl alloy tubes for aerospace applications.
Abstract
The grain size of TiAl alloy castings prepared by traditional casting process is coarse, thus showing poor mechanical properties. In this study, a new type of high performance Ti-46Al alloy tube prepared by vacuum centrifugal casting technology was introduced. This research comprehensively examined the influence of pouring time on the microstructure and mechanical performance of the castings, employing both experimental approaches and ProCast simulation methodologies. The findings indicate that prolonging the pouring time facilitates a microstructural evolution from coarse columnar grains to refined equiaxed grains. Under the condition of pouring temperature of 1,600 °C, rotation speed of 800 r·min-1 and pouring time of 6 s, the tensile strength of Ti-46Al alloy at room temperature reaches 650 MPa, and the tensile strength at 800 °C reaches 705 MPa, which is significantly higher than that of traditional as-cast Ti-Al alloy.
1. Introduction
TiAl-based alloys, as novel lightweight materials, exhibit high strength, low density, and outstanding corrosion resistance, rendering them an ideal choice for aerospace applications [1, 2]. Specifically, TiAl alloy tubes are primarily utilized in the fabrication of aircraft structural components, including fuselage, engine parts, and landing gear. In the traditional casting process, the lamellar structure and grain size of TiAl alloy castings are coarse and difficult to control, thus showing poor mechanical properties [3-5]. This study introduced a method for preparing high-performance TiAl alloy tubes using vacuum centrifugal casting technology.
Among precision casting techniques, centrifugal casting emerges as a well-established and prominent method [6, 7]. This technique disrupts dendritic structures through the application of external forces and redistributes solute particles, facilitating the formation of alloy microstructures with enhanced structural density, uniform filling, and minimized defects [8]. The centrifugal force field plays a pivotal role in purging impurities from the melt, promoting dendritic remelting, and inducing grain boundary fracture through fluid flow and vibration. Additionally, it accelerates heat dissipation from the melt, aiding in the control of grain nucleation [9]. Consequently, centrifugal casting is highly efficient, and under vacuum conditions, adept at achieving monolithic forming of alloy tubes, improving their microstructures and enhancing mechanical properties [10]. For instance, Ti-xAl-8Nb-3.6C-0.8Mo in-situ composites prepared by Lapin et al. [11] using centrifugal casting exhibited higher Vickers hardness and matrix Vickers microhardness values. Similarly, Ti-45Al-2W-xC alloy was prepared by Kamyshnykova et al. [12] using centrifugal casting method. The alloy exhibited good mechanical properties after heat treatment.
However, centrifugal casting is associated with extended production lead times and higher costs [13]. To mitigate these challenges, computer simulation is employed to optimize the production time and cost of centrifugal cast alloys [14, 15]. ProCAST, a casting simulation software, excels in analyzing the filling and solidification behavior during centrifugal casting processes. In a related study, Chang et al. [16] developed a coupled stochastic model to predict solidification microstructures in centrifugal casting. Their research suggested that a combination of moderate mold rotation speed, low melt superheat, low mold preheating temperature, and slightly higher solute concentration favors the formation of fine equiaxed structures in vertical centrifugal casting.
As a specific composition of β-type γ-TiAl alloy, Ti-46Al alloy has significant advantages in light weight compared with other Ti-Al alloys. As a crucial parameter in centrifugal casting, the pouring time has a direct impact on the grain size and mechanical properties of the castings. However, there currently lacks systematic research on the influence of pouring time on the centrifugal casting process of Ti-46Al alloy. In this study, numerical simulations of Ti-46Al alloy castings under different pouring times were conducted using ProCAST software to analyze the solidification behavior of the melt under high gravity conditions. Multiple sets of castings with varying pouring times were prepared using a vacuum centrifugal casting apparatus. The microstructures, tensile properties and Vickers hardness of the castings were examined and tested at room temperature. The study results provide theoretical support and technical insights for vacuum centrifugal casting of Ti-46Al alloy.
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Gang Huang, Qian Dang, Cong-cong Su, Jing Zhao, Chi Zhang, Guo-huai Liu, Zhao-dong Wang (2025). Effect of pouring time on microstructure and mechanical properties of centrifugal cast Ti-46Al alloy tubes. China Foundry. https://doi.org/10.1007/s41230-025-3171-9
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Frequently Asked Questions
What is the effect of pouring time on the microstructure of Ti-46Al alloy tubes?
Prolonging the pouring time facilitates a microstructural evolution from coarse columnar grains to refined equiaxed grains, improving the uniformity and mechanical properties of the castings.
What are the optimal casting parameters for high-performance Ti-46Al alloy tubes?
The optimal parameters are a pouring temperature of 1,600 °C, rotation speed of 800 r·min-1, and pouring time of 6 s, yielding tensile strengths of 650 MPa at room temperature and 705 MPa at 800 °C.
How does vacuum centrifugal casting improve the properties of TiAl alloys?
Vacuum centrifugal casting disrupts dendritic structures, redistributes solute particles, purges impurities, and accelerates heat dissipation, leading to refined microstructures and enhanced mechanical properties.
What role does ProCAST simulation play in this study?
ProCAST simulation is used to analyze the filling and solidification behavior under high gravity conditions, helping to predict microstructural evolution and optimize casting parameters.
What are the potential applications of Ti-46Al alloy tubes?
Ti-46Al alloy tubes are primarily used in aerospace structural components such as fuselage, engine parts, and landing gear, due to their high strength, low density, and corrosion resistance.
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