How to innovate high temperature titanium alloy preparation technology to overcome engineering problems?
In view of the stringent requirements of high-temperature rotating parts of aircraft engines on materials, new high-temperature titanium alloys represented by 600℃ high-temperature titanium alloys, flame-retardant titanium alloys, TiAl alloys and SiCf/Ti composite materials are facing the key challenge of transitioning from laboratory research to engineering applications. The technical difficulties are concentrated on the systematic breakthroughs in material design, preparation technology and performance optimization, and the core lies in achieving organizational control and performance stability improvement through advanced processing technology.
1. Breakthrough in high-purity ingot melting process. In response to the ingot preparation problems of high-alloyed materials such as TA29, TB12 and TiAl alloys, my country has formed a multi-dimensional process solution: Vacuum consumable melting optimization: By increasing the number of melting times (3-4 times), accurately controlling the melting current (±5% accuracy), increasing the current gradient and the water cooling intensity of the crucible, the ingot component segregation rate is reduced to below 0.8%; Plasma cold hearth technology upgrade: Plasma cold hearth melting (PCHM) is used in the preparation of TiAl alloys. Through 1600℃ high-temperature refining and electromagnetic stirring, high-density inclusions (size ≤50μm) are significantly removed, and the oxygen content is stably controlled within 800ppm. At present, my country has built 8 industrial PCHM equipment, with a single melting capacity exceeding 1.2 tons, providing high-purity billets for engine rotating parts. 2. Precision forging technology for large-size bars. To meet the needs of large components such as integral blade disks and blade rings, the focus is on breakthroughs in the control of uniformity of large-size bar organization: High-temperature extrusion blanking process: In view of the poor plasticity of TB12 and TiAl alloy ingots, the β phase region (1000-1100℃) multi-directional extrusion technology is adopted to achieve a deformation of more than 70%, and the grain size is refined from 500μm in the cast state to 50μm; Multi-directional die forging: Four-fire variable temperature forging is implemented on a 36,000-ton hydraulic press. Through gradient deformation in the α+β two-phase region (deformation rate 0.01-0.1s⁻¹), the streamline integrity of the forging is >95%, and the batch performance dispersion is reduced by 40%. After a certain type of high-pressure compressor rotor forging is treated by this process, the 650℃ high-temperature creep life is increased to 1800 hours. 3. Precision control technology of microstructure: To solve the problem of high-temperature creep-fatigue interaction, a full-process organization control system is established: Directed control of α phase morphology: Through two-stage heat treatment (950℃ solution + 750℃ aging), the thickness of the lamellar α phase is controlled at 0.2-0.5μm, and the distance between adjacent β phases is ≤1μm, which significantly improves the fatigue crack growth resistance of Ti60 alloy (ΔKth value reaches 8MPa√m); Texture homogenization design: Electron backscattered diffraction (EBSD) is used to monitor the evolution of forging texture in real time, and the forging path is optimized through the dynamic recrystallization model, so as to reduce the texture strength index of TiAl alloy (γ-TiAl) from 7.3 to 2.1, and the anisotropy elimination rate reaches 80%. 4. Surface integrity and residual stress control To ensure the service reliability of high-temperature components, innovative developments are made: Laser shock strengthening technology: A 4J/cm² energy density laser beam is used to process the blade groove, introducing a 1.2mm deep residual compressive stress layer, which increases the micro-motion fatigue life of TiAl alloy blades by 3 times; Multi-physics field residual stress evaluation: Combining X-ray diffraction and neutron diffraction technology, a three-dimensional residual stress map database for forgings is established, and the internal stress peak of the blade forging is reduced from 450MPa to below 80MPa through the hot isostatic pressing (HIP) process (920℃/100MPa/2h). Progress in engineering application The high-pressure turbine disk of a certain type of engine in my country is made of TiAl alloy. After the optimization of the above process system: The endurance strength at 650℃ exceeds 750MPa, which is 35% lighter than traditional nickel-based alloys; The low-cycle fatigue life (R=0.1) is increased from 15,000 times to 42,000 times; The batch production qualification rate is increased from 62% to 88%, and the manufacturing cost of a single piece is reduced by 27%. With the promotion and application of intelligent forging production lines (integrated digital twins and machine learning algorithms), the engineering application of high-temperature titanium alloys is accelerating the breakthrough of the "double barriers" of performance and cost, providing key material support for the sixth-generation aircraft engines.
Company: Baoji Dynamic Trading Co., Ltd
Country:China
Add:Baoti road,Jintai,Baoji city,Shaanxi,China
Cel:+86 18391896637(WHATSAPP)/18391894207
Gmail:alisa@jmyunti.com
Website:www.jm-titanium.com
