Ni-Based Superalloy for High-Temperature Aircraft Engine Case Fatigue
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Solution Overview
Problem
Conventional Ni-based heat resistant superalloys face challenges in maintaining high-temperature strength and low-cycle fatigue characteristics when exposed to elevated temperatures, particularly in aircraft engine cases, leading to deformation or breakage due to continuous stress cycles, and lack sufficient performance in high-temperature environments exceeding 700°C.
Innovation Solution
A Ni-based heat resistant superalloy with controlled alloy components and composition ranges, including specific amounts of Co, Cr, Al, Ti, Mo, W, B, and C, along with a controlled difference between the solvus temperature of M6C-type carbide and y' phase, to enhance solid solution strengthening and suppress grain growth, resulting in a homogeneous microstructure with improved workability and high-temperature performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional Ni-based heat resistant superalloys are used in aircraft engine cases, then basic strength and corrosion resistance are provided, but high-temperature strength and low-cycle fatigue characteristics deteriorate at temperatures exceeding 700°C
Solution Approach 1:
The patent applies parameter changes by precisely controlling the chemical composition parameters of the superalloy. Specifically, it limits Cr to 12-17%, Co to 4-11%, Al to 2-4%, Ti to 2-4%, Mo to 5.5-10%, and W to 1.1-4%, while controlling the difference between solvus temperatures of M6C-type carbide and γ' phase to -30°C to +40°C. This compositional parameter optimization enables the alloy to maintain both high strength and excellent low-cycle fatigue resistance at temperatures exceeding 700°C.
Solution Approach 2:
The patent creates a composite microstructure by controlling the precipitation of γ' phase and M6C-type carbides within the γ matrix. The dual-precipitation strengthening mechanism combines γ' phase reinforcement with M6C carbide dispersion, forming a composite microstructure that simultaneously improves high-temperature strength and suppresses grain growth, thereby enhancing low-cycle fatigue characteristics.
2Use of energy by moving object
If higher combustion temperatures are implemented to improve fuel efficiency, then energy performance improves, but material deformation and breakage increase due to continuous stress cycles
Solution Approach 1:
The patent enables higher combustion temperatures by optimizing the compositional parameters of the superalloy. The controlled ranges of alloying elements and the regulated solvus temperature difference create a microstructure that maintains stability under thermal cycling, allowing engines to operate at higher temperatures for improved fuel efficiency without suffering from material deformation or breakage.
Solution Approach 2:
The patent applies beforehand cushioning by pre-establishing a stable microstructure through controlled precipitation of γ' phase and M6C-type carbides during alloy processing. This pre-formed microstructure acts as a cushion against thermal stress and continuous loading cycles, preventing deformation and breakage before they can occur during high-temperature operation.
3Strength
If alloy composition is optimized for high-temperature strength, then tensile characteristics improve, but workability may deteriorate
Solution Approach 1:
The patent resolves the contradiction between tensile strength and workability through careful parameter optimization. By setting specific compositional ranges (Cr: 12-17%, Co: 4-11%, Al: 2-4%, Ti: 2-4%, Mo: 5.5-10%, W: 1.1-4%) and controlling the solvus temperature difference to -30°C to +40°C, the alloy achieves excellent tensile characteristics while maintaining adequate workability for manufacturing aircraft engine cases.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The superalloy exhibits excellent tensile characteristics, low-cycle fatigue resistance, and workability, enabling the production of larger aircraft engine cases suitable for higher combustion temperatures, thus enhancing fuel efficiency and maintaining consistent performance over time.
Implementation Method 1
enhance solid solution strengthening
Implementation Method 2
suppress grain growth, resulting in a homogeneous microstructure
Data Source
Figure 1~2
Figure 3
AI summary
Provided are a Ni-based heat resistant superalloy for aircraft engine cases excellent in high-temperature characteristic such as tensile characteristics and low-cycle fatigue characteristics in a high-temperature range and also excellent in workability, and an aircraft engine case formed of the same. The Ni-based heat resistant superalloy has composition containing, by mass, Co: 4.0 to 11.0%, Cr: 12.0 to 17.0%, Al: 2.0 to 4.0%, Ti: 2.0 to 4.0%, Al + Ti: 4.6 to 6.7%, Mo: more than 5.5 to 10.0%, W: more than 0 to 4.0%, B: 0.001 to 0.040%, C: 0.02 to 0.06%, Zr: 0 to 0.05%, Mg: 0 to 0.005%, P: 0 to 0.01%, Nb: 0 to 1.0%, Ta: 0 to 1.0%, and Fe: 0 to 2.0%, and the balance of Ni with inevitable impurities, and is suitable for aircraft engine cases.