Nickel-Based Superalloy Composition for Heat-Treatment Crack Resistance
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Solution Overview
Problem
Nickel-based superalloys used in additive manufacturing, such as IN 738LC, are prone to cracking during heat treatments due to tensile residual stress, particularly in components like aircraft engine turbines.
Innovation Solution
A nickel-based superalloy with specific compositions (13.50% to 15.50% Cr, 5.05% to 5.55% Mo, 5.75% to 6.25% W, 5.90% to 6.40% Ta, 2.70% to 3.00% Al, 0.010% to 0.060% Zr, 0.045% to 0.105% C, 0.002% to 0.010% B, up to 9.00% Co, up to 1.00% Nb, and up to 0.50% Ti) is used, along with a production method involving energy beam application to form layers, reducing the strain aging cracking index to below 3.9 and minimizing γ' phase precipitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If additive manufacturing is performed using conventional nickel-based superalloy powder (IN 738LC), then high-temperature strength and oxidation resistance are achieved, but heat treatment-induced cracking occurs due to tensile residual stress
Solution Approach 1:
The patent applies parameter changes by precisely controlling the chemical composition parameters of the nickel-based superalloy. Specifically, it limits Cr to 13.50-15.50%, Mo to 5.05-5.55%, W to 5.75-6.25%, Ta to 5.90-6.40%, Al to 2.70-3.00%, and controls trace elements (Zr: 0.010-0.060%, C: 0.045-0.105%, B: 0.002-0.010%). This compositional parameter control modifies the material's microstructure and reduces the strain aging cracking index to below 3.9, thereby preventing heat treatment-induced cracking while maintaining high-temperature strength
Solution Approach 2:
The patent creates a composite material system by combining multiple alloying elements in specific proportions to achieve synergistic effects. The nickel-based superalloy integrates Cr, Mo, W, Ta, Al, Zr, C, and B elements that work together to form a microstructure with optimized γ' phase distribution and reduced residual stress, resulting in a material that resists both cracking and maintains high-temperature performance
2Stress or pressure
If post-production heat treatment is applied to relieve stress, then residual stress is reduced, but cracking occurs due to tensile residual stress in certain shapes
Solution Approach 1:
The patent applies preliminary action by pre-controlling the alloy composition before manufacturing to prevent the formation of high residual stress states that would lead to cracking during heat treatment. The specific compositional parameters (particularly Cr: 13.50-15.50%, Mo: 5.05-5.55%, W: 5.75-6.25%, Ta: 5.90-6.40%) are designed in advance to ensure the material has inherent resistance to heat treatment-induced cracking, eliminating the need for stress relief treatments
3Strength
If γ' phase precipitation is increased for strengthening, then high-temperature strength is improved, but strain aging cracking index increases leading to cracking
Solution Approach 1:
The patent applies parameter changes by optimizing the composition parameters to achieve a balanced microstructure. It controls Al content (2.70-3.00%) to regulate γ' phase formation while limiting Cr (13.50-15.50%) and Mo (5.05-5.55%) to control the strain aging cracking index. This parameter optimization maintains sufficient γ' phase for high-temperature strength while keeping the cracking index below 3.9
Solution Approach 2:
The patent applies local quality by creating a non-uniform microstructure with controlled γ' phase distribution. The specific alloy composition promotes localized γ' phase precipitation in regions where it provides strengthening while avoiding excessive precipitation in regions prone to cracking. This spatial differentiation of microstructural features allows simultaneous achievement of strength and cracking resistance
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 solution provides a nickel-based superalloy resistant to heat treatment-induced cracking, maintaining high-temperature strength and reducing solidification cracks, as demonstrated by comparative tests.
Implementation Method 1
applying an energy beam to the layer to melt and solidify at least a portion of the layer
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A nickel-based superalloy according to one embodiment contains, in percent by mass, 13.50% to 15.50% Cr, 5.05% to 5.55% Mo, 5.75% to 6.25% W, 5.90% to 6.40% Ta, 2.70% to 3.00% Al, 0.010% to 0.060% Zr, 0.045% to 0.105% C, 0.002% to 0.010% B, up to 9.00% Co, up to 1.00% Nb, and up to 0.50% Ti.