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English
The aerospace industry has very high requirements for the strength, lightweight, and high temperature resistance of components, and forging technology has become a key manufacturing process due to its dense structure and excellent mechanical properties. The following are specific applications and technological breakthroughs:
1、 Core requirements for aerospace forgings
Comparison of indicator requirements for civilian forgings
Tensile strength ≥ 1200MPa (titanium alloy) Automotive parts typically range from 500-800MPa
Weight reduction of more than 30% (structural optimization+lightweight materials) civilian parts weight reduction demand<15%
Temperature resistance working temperature: -60 ℃~800 ℃ (nickel based alloy) ordinary mold steel temperature resistance ≤ 600 ℃
Fatigue life>10 ⁷ cycles (without cracks) for civil parts, usually 10 ⁶ cycles
2、 Key materials and forging processes
1. Typical aerospace forging materials
Forging difficulties in material application scenarios
Titanium alloy (Ti-6Al-4V) engine blades and fuselage frames have high deformation resistance and require isothermal forging
Nickel based high-temperature alloy (Inconel 718) turbine disk, combustion chamber forging temperature window narrow (± 20 ℃)
Aluminum alloy (7075-T74) aircraft skin and landing gear need to be temperature controlled to avoid overheating (<470 ℃)
Ultra high strength steel (AISI 4340) landing gear struts and transmission shafts require ultra-fine grain forging (grain size ≤ 5 μ m)
2. Advanced forging technology
(1) Isothermal forging
Process characteristics: The mold and billet are at the same temperature (titanium alloy: 900-950 ℃), with a strain rate of ≤ 0.01s ⁻¹
Advantages:
Uniform organization (grain size ASTM 8-10)
Reduce residual stress (70% lower than conventional forging)
Application: US F-22 fighter jet titanium alloy fuselage frame (reduced weight by 20%)
(2) Powder metallurgy forging (PM forging)
Process: Pre alloyed powder → Hot isostatic pressing (HIP) → Quasi dense forging
Advantages:
Material utilization rate>95% (traditional forging only 50%)
Can prepare difficult to deform alloys (such as TiAl intermetallic compounds)
Application: GE aviation engine high-pressure turbine disc (fatigue life increased by 3 times)
(3) Superplastic Forming
Condition: Fine grained material (grain size<10 μ m)+high temperature and low speed (titanium alloy: 850 ℃, 10 ⁻³ s ⁻¹)
Advantages:
One time forming of complex structures (such as hollow blades)
Surface accuracy Ra ≤ 1.6 μ m (without mechanical processing)
Case: Airbus A380 wing ribs (reduced weight by 15%)
3、 Typical aerospace forging case
1. Key components of the engine
Requirements for material and process performance of components
Turbine disk Inconel 718 radial forging+isothermal precision forging, creep life>100000 hours at 650 ℃
Compressor blade Ti-6Al-4V superplasticity forging+diffusion connection fatigue strength ≥ 550MPa
Combustion chamber liner Haynes 230 multi-directional forging resistant to 1100 ℃ oxidation
2. Structural components of the aircraft body
Landing gear (AISI 4340 steel):
Adopting deformation heat treatment (direct quenching after forging), tensile strength ≥ 2000MPa
Wing beam (Al Li alloy):
Quasi dense forging+aging strengthening, 25% lighter than traditional aluminum alloys
4、 Technical Challenges and Solutions
1. Forming of large-sized forgings (such as integral turbine discs)
Problem: Nickel based alloy discs with a diameter greater than 1.5m are prone to segregation
Plan:
Multi directional forging: eliminating internal defects through triaxial compressive stress
Local induction heating: control temperature difference ≤ 30 ℃
2. Residual stress control
Measures:
Deep cold treatment after forging (-196 ℃ × 24h) → residual stress reduced by 50%
Laser shock peening (LSP): surface compressive stress enhances fatigue life
3. Digitization and Intelligence
Process monitoring:
Real time monitoring of forging temperature with infrared thermal imager (accuracy ± 5 ℃)
Feedback deformation resistance of force displacement sensor (optimizing forging parameters)
Simulation:
DEFORM software predicts grain evolution (deviation from actual<10%)
5、 Industry benchmark comparison
Technical indicators: Traditional forging, aerospace grade forging (such as PCC Group)
Dimensional accuracy ± 1mm ± 0.2mm (CNC precision forging)
Uniformity of organization, grain size of 6-8 levels, full cross-section of 10 levels or above
Defect detection rate: 90% ultrasonic testing, industrial CT+phased array ultrasound (99.9%)
6、 Future Trends
Lightweight integrated design:
3D printing preform+quasi dense forging (such as topology optimized hollow structure)
Application of new materials:
Titanium aluminum alloy (TiAl), oxide dispersion strengthened alloy (ODS)
Green forging:
Cold forging/warm forging replaces hot forging (saving over 40% energy)
Summary
The core of aerospace forging technology is the "three highs":
High material performance (ultrafine grain, low segregation)
High process control (isothermal/superplasticity/multi-directional forging)
High testing standards (industrial CT+fatigue testing)
Through technological innovation, modern aviation forgings have achieved "weight reduction without strength reduction", becoming the cornerstone of aircraft safety and performance.
