Design and processing technology of high-temperature titanium alloy materials
600℃ high-temperature titanium alloy, flame-retardant titanium alloy, TiAl alloy, and SiCf/Ti composite materials are new high-performance high-temperature titanium alloys. Compared with ordinary titanium alloy materials, its technological maturity is lower. In view of the service characteristics and design requirements of advanced engines, especially rotating parts used in high-temperature environments, a large amount of engineering application research needs to be carried out, such as creep-fatigue-environment interaction in high-temperature environments, flame retardant properties, and the effect of microstructure on fatigue Impact on performance, surface integrity technology, internal surface residual stress analysis of forgings and parts and its impact on performance, service life prediction and failure analysis, etc., to solve key technologies such as material design, manufacturing and processing technology related to engineering applications.
High purification and homogenization control technology for industrial tablet ingredients
TA29, TB12, and TiAl alloys have complex alloy compositions, high alloying element content, and low plasticity. The preparation of these alloy ingots is difficult. The main manifestations are: when the shape of the ingot expands, cracking is prone to occur due to solidification thermal stress, and the composition uniformity is controlled. This is difficult and prone to separation. When using the traditional vacuum consumable electrode electric arc furnace melting process, the number of melting times should be appropriately increased, and the melting current, lifting current, ingot size, crucible cooling method, etc. should be controlled. For TiAl alloy, the plasma cooling bed melting process can be used to produce ingots. The cooling bed smelting process can effectively remove inclusions and improve component segregation, which is particularly important for titanium alloy materials used in key rotating parts of engines. Our country already has multiple plasma cooling bed smelting equipment and has the capabilities and conditions for laboratory research and industrial production.
Preparation technology for large-size bars and special forgings
Titanium alloy raw materials for aviation forgings generally use rods. Large forgings such as wheel discs, casings, blisks, and fan blades generally use large-size bars. For small compressor blades and turbine blade forgings, small size rods are used. . As advanced engines tend to adopt the structural form of integral blisks and integral leaf rings, the specifications of corresponding forgings and bars continue to increase. Controlling the structural uniformity of large-size bars is crucial to ensuring the quality of forgings, which requires selecting appropriate forging equipment and optimizing the design of the forging process. For TB12 and TiAl alloy ingots, because the as-cast metal has high forging deformation resistance, low process plasticity, is sensitive to deformation temperature, and is prone to forging cracks, the ingot should use a high-temperature extrusion blanking process to prepare large-size bars, not only It can improve the uniformity of deformation, ensure sufficient deformation, and also improve the production efficiency and batch stability of rods.
Due to the anisotropy of the α phase, the microstructure and crystal texture of titanium alloys are the main factors affecting the mechanical properties. Controlling the microstructure morphology of forgings and the uniformity of microstructure and texture can not only improve the average performance level, but also improve the creep fatigue interaction performance of the part, that is, the load-bearing fatigue performance, and reduce the fatigue life. Quantities of different batches. Dispersion of performance data for secondary components. For these new high-temperature titanium alloys, especially TiAl alloys, the introduction of ordered structures makes the texture problem more complex and important, and the impact on high and low cycle fatigue properties and load-bearing fatigue properties is also more complex. The organization and texture must be strictly controlled during the preparation of bars and forgings.
Mechanical processing technology of integral blisk and integral leaf ring parts
Due to the continuous improvement of the performance level of advanced engines, integral blisks, integral blade rings, etc. have become a development trend. The blisk blades have a complex structure, poor channel smoothness, thin blades, large bending and torsion, poor rigidity, and are easily deformed. The requirements for geometric accuracy and overall quality level during design are getting higher and higher, and the requirements for machining and surface integrity are getting higher and higher. Guarantees are becoming increasingly difficult [30]. For compressor blisks and integral blade rings with smaller blade sizes, the blades are generally processed using high-speed CNC milling to control the processing deformation of the parts. Vibration finishing stress relief technology is used to improve the residual stress distribution on the surface of the part and then process the blade parts. The profile surface is ground and abrasive flow polished. The blade shape has high dimensional accuracy, the blade shape error is less than 0.1mm, and the blade shape surface roughness Ra reaches the 0.2μm level, which improves the surface quality and surface integrity of the part. The surface processing of TiAl alloy blades should use electrochemical methods.
