Formable Nickel Superalloy Single Crystal Composition
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Solution Overview
Problem
Current superalloys used in gas turbine components other than blades, such as discs, side plates, and W-seals, face challenges in temperature performance due to the presence of grain boundaries, which affect creep resistance and formability, especially when these components require bending, forging, or welding processes.
Innovation Solution
A formable nickel-based superalloy composition with a reduced volume fraction of γ' precipitates (40-55%) is developed, allowing for single crystal casting and improved formability and weldability, while maintaining marginal loss in creep capability and oxidation resistance, suitable for components operating at lower temperature ranges (1500-1700°F).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the volume fraction of γ' precipitates is increased to 60-65% to improve creep resistance, then creep resistance is improved, but formability deteriorates
Solution Approach 1:
The patent changes the volume fraction parameter of γ' precipitates from the conventional 60-65% to a reduced range of 40-55%. This parameter modification enables the material to achieve adequate creep resistance while significantly improving formability, allowing bending and shaping operations that would be difficult or impossible with higher precipitate fractions.
2Strength
If grain boundaries are eliminated by using single crystal structure to improve creep resistance, then creep resistance is improved, but formability and weldability deteriorate
Solution Approach 1:
The patent applies local quality by creating a hybrid microstructure where the bulk material maintains a polycrystalline structure with controlled grain boundaries for formability, while the critical precipitate distribution provides localized creep resistance. This allows different regions or aspects of the material to have optimized properties for their specific functions.
3Strength
If refractory elements such as Ta and Re are added to improve creep resistance, then creep resistance is improved, but melting point decreases due to C, B, Zr and Hf elements
Solution Approach 1:
The patent modifies the concentration parameters of alloying elements, specifically limiting C, B, Zr, and Hf to low levels (C: 0.01-0.05%, B: 0.003-0.01%, Zr: 0.01-0.05%, Hf: 0.01-0.05%) while maintaining Ta (2-4%) and Re (2-4%). This parameter optimization minimizes melting point depression while preserving creep resistance enhancement from the refractory elements.
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 reduced precipitate volume fraction enhances creep resistance and formability, enabling easier processing and improved temperature performance for non-blade components, while maintaining suitable mechanical properties and oxidation resistance.
Implementation Method 1
a two phase γ/γ' precipitation hardenable nickel base superalloy
Data Source
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AI summary
A formable nickel based superalloy composition including a two phase γ/γ' precipitation hardenable nickel base superalloy with a sum of primarily γ' forming elements in atom % is in the range of about 10-16, forming about a 40-64 volume % of the γ' precipitate, cast in form of a single crystal.