Application of high temperature alloys in aviation field
1. Four hot end components
High-temperature alloys are mainly used in the four hot-end components of aeroengines:
Combustion chamber: The combustion chamber is the source of mechanical energy generation. The combustion chamber walls and combustion chamber are mainly made of high-temperature alloy materials because they need to withstand temperatures above 800°C. The material needs to have good fatigue resistance, strong oxidation resistance, and good cutting performance.
- Turbine blades: Turbine blades are the most critical components of aeroengines. Turbine blades must withstand high temperatures and must withstand large centrifugal stress, vibration stress, thermal stress, etc. The main material used in turbine blade manufacturing is cast high-temperature alloy. Currently, single crystal high-temperature alloys are widely used in manufacturing. This alloy has tensile, durable, creep fatigue, oxidation resistance and hot corrosion resistance properties.
- Guide vane: The guide vane is a component used to adjust the flow direction of the gas coming out of the combustion chamber. It is one of the parts that suffers the greatest thermal shock on the aeroengine. The material has high temperature oxidation resistance, good resistance to thermal fatigue and mechanical fatigue, high thermal conductivity and low thermal expansion coefficient.
- Turbine disc: When the turbine disc is working, the rim temperature reaches 550-750°C, while the wheel center temperature is only about 300°C, causing a large temperature difference across the entire component; it bears significant centrifugal force when rotating; it bears large stresses during startup and parking. fatigue cycle. The material must have high strength. Good plasticity and good thermal fatigue resistance.
2.Aviation fasteners
The main fastener products on aircraft engines include various types of bolts, keyed screw piles, self-locking nuts, thread sleeves, pins, pipe fittings and connectors, etc.
- High temperature and high strength bolts and screws
Bolts and screws made of materials such as GH4169 are currently the most widely used high-temperature and high-strength fasteners in aero-engines. After heat treatment, the tensile strength of such parts reaches σb ≥ 1250Mpa, and the threads of this type of high-strength fasteners are processed by warm rolling. Technology is the direction of research and development.
- Tighten the bolts
Engine turbine bolts and high-precision slender tightening bolts are key load-bearing parts of aeroengines. This type of fasteners are generally processed from forging blanks, and the materials are mainly high-temperature alloys and titanium alloys. In addition to high-temperature, high-strength, and high-precision performance requirements, such parts also have structural forms and requirements for slender shaft parts. The processing difficulties of this type of parts mainly lie in high-strength thread rolling and processing deformation control of slender shafts.
- Keyed locking screw piles and screw sleeves
Keyed locking screw piles and threaded sleeves are a newly developed aviation fastener connection technology in recent years. This connection technology is mainly transformed from the traditional combined connection method of interference threads and locking discs. It is a pin-key locking method, making the assembly locking structure more compact, more reasonable, and more reliable in preventing loosening.
- High temperature alloy self-locking nut
Self-locking nuts. In the past, the form of this type of fastener was relatively simple, mainly made of alloy steel and stainless steel. With the continuous advancement of aero-engine technology, most of the self-locking nuts of engine fasteners are now made of high-temperature alloy materials. The lock deformation forms include two-point, three-point, four-point, straight groove, inclined groove and other closing forms. The standards implemented include HB, GJB and the special technical standards of each developed model.
Special self-locking nut
With the gradual improvement of domestic and foreign advanced aerospace engine technology, more reliable, simpler and lighter spindle rotor fasteners are needed to fasten parts on high-speed rotating spindles. The diameter and thickness ratios of this special self-locking nut on a high-speed rotating spindle are generally 4:1, 6:1, and 10:1. The self-locking deformation zone of this type of special self-locking nut is short, and the molding process is difficult, which affects the material. The requirements for heat treatment control, metallurgical quality, and self-locking stability are extremely high.
High temperature alloys such as A286 (GH2132), GH2696, GH3030, inconel718 (GH4169), GH4698, Waspaloy (GH738) are all commonly used materials for aerospace fasteners.
3.Other components
Used for components such as receivers, rings, afterburners, and tail nozzles.
