Nickel Super Alloy Grain Control via Deformation
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Solution Overview
Problem
Nickel-based super alloys (NiSa) face challenges in machinability and achieving optimal mechanical properties, particularly in complex parts, due to uniform grain size distribution from traditional casting methods, which limits creep resistance and fatigue performance.
Innovation Solution
A method involving obtaining a NiSa article with fine grains, mechanically deforming specific regions, and heat treating to achieve coarse grains, allowing for adaptive grain size distribution that enhances creep resistance and fatigue performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If traditional casting method is used to manufacture NiSa parts, then the parts can be produced with uniform grain size distribution, but the mechanical properties are not optimal for complex parts and creep resistance is limited
Solution Approach 1:
The patent applies local quality by creating different grain sizes in different regions of the NiSa part. Specifically, fine grains are maintained in regions requiring fatigue resistance while coarse grains are developed in regions requiring creep resistance. This is achieved through selective mechanical deformation followed by heat treatment, where only specific regions undergo deformation to trigger grain growth during subsequent heat treatment, thereby optimizing mechanical properties locally rather than uniformly throughout the entire part.
2Shape
If PBF-EB method is used to manufacture NiSa parts, then complex parts can be produced, but non-weldable alloy cannot be produced and local control of microstructure is difficult
Solution Approach 1:
The patent applies preliminary action by first mechanically deforming specific regions of the NiSa part before heat treatment. This pre-deformation creates a localized microstructural state that predisposes those regions to undergo grain growth during subsequent heat treatment. By performing this deformation step in advance, the patent enables precise control over which regions will develop coarse grains versus fine grains, achieving local microstructure control that was difficult with PBF-EB method alone.
3Strength
If casting method is used, then large coarse grain size is obtained providing good creep resistance, but fatigue performance is reduced
Solution Approach 1:
The patent resolves this contradiction by applying local quality - creating fine grains in regions requiring fatigue resistance and coarse grains in regions requiring creep resistance. Through selective mechanical deformation followed by heat treatment, the patent enables different grain sizes to coexist within the same NiSa part, optimizing both fatigue and creep performance in their respective regions rather than compromising one for the other.
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 method enables the creation of NiSa parts with optimized mechanical properties by maintaining fine grains in non-deformed regions and increasing creep resistance and reducing fatigue in deformed regions, improving overall performance for aerospace applications.
Implementation Method 1
mechanical deformation is performed by plastic deformation
Implementation Method 2
heat treating the NiSa article to obtain coarse grains in the one or more regions
Data Source
AI summary
There is provided a method of treating a nickel base super alloy (NiSa) article. First, the NiSa article having fine grains is obtained. The NiSa article has a uniform distribution of the fine grains and substantially uniform mechanical properties throughout. One or more regions within the NiSa article are mechanically deformed. Then, the NiSa article is heat treated to obtain coarse grains in the one or more regions, the coarse grains having a size that is larger than that of the fine grains of the NiSa article outside of the one or more regions.