Bonded Dual-Alloy Turbine Rotor Disk for Rim Creep Resistance
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Solution Overview
Problem
Gas turbine engine disks face challenges in maintaining mechanical properties across radial temperature and stress gradients, with the rim portion experiencing severe creep and fatigue crack growth, and the hub portion facing high stress and fatigue, requiring alloys with specific resistance properties for optimal performance.
Innovation Solution
A turbine rotor disk is designed with a radially inner wrought nickel alloy for high yield strength and a radially outer cast nickel alloy as single crystal or with large grain size, bonded together using solid-state techniques like inertia or diffusion bonding to achieve customized mechanical properties across different disk regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a single alloy is used for the entire disk, then manufacturing is simpler, but the disk cannot simultaneously achieve high creep resistance in the rim and high tensile strength in the hub
Solution Approach 1:
The disk is divided into two distinct alloy regions: a first alloy for the hub portion and a second alloy for the rim portion. This segmentation allows each region to have optimized mechanical properties suitable for its specific operating conditions, resolving the contradiction between achieving high strength/creep resistance and maintaining manufacturing simplicity.
Solution Approach 2:
Different alloy compositions and microstructures are applied to different radial locations of the disk. The hub region receives an alloy optimized for high tensile strength and fatigue resistance, while the rim region receives an alloy optimized for creep and hold time fatigue crack growth resistance. This local quality approach enables simultaneous optimization of both regions without requiring a completely complex multi-component assembly.
2Reliability
If different alloys are used for hub and rim portions, then mechanical properties are optimized for each region, but manufacturing complexity increases
Solution Approach 1:
The disk is manufactured as a single casting with predetermined alloy composition variations built into the mold design. The alloy composition is varied radially during the casting process itself, rather than requiring post-casting assembly of separately manufactured hub and rim components. This preliminary action approach optimizes reliability through region-specific alloy properties while avoiding the manufacturing complexity of assembling multiple components.
Solution Approach 2:
The disk employs a composite alloy structure where different nickel-based superalloys are combined within a single component. The first alloy (e.g., containing aluminum and titanium) provides high tensile strength for the hub, while the second alloy (e.g., containing boron and hafnium) provides creep resistance for the rim. This composite material approach achieves optimized reliability across regions while maintaining the simplicity of a single-monopiece construction.
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 enhanced hold time fatigue crack growth resistance, high temperature creep resistance, and high tensile strength, improving the efficiency and performance of gas turbine engines by optimizing mechanical properties in both the rim and hub regions.
Implementation Method 1
bonding the first and second preforms together can include diffusion bonding the first and second preforms together
Implementation Method 2
bonding the first and second preforms together can include inertia bonding the first and second preforms together
Data Source
AI summary
A turbine rotor disk and a method of making the turbine rotor disk using solid state bonding techniques are disclosed. The turbine rotor disk includes a radially inner portion comprising a wrought nickel alloy having a yield strength of at least 126 ksi at 1,000° F. The turbine rotor disk also includes a radially outer portion bonded to the radially inner portion, said radially outer portion comprising a cast nickel alloy configured as a single crystal or with a grain size of ASTM 2 or larger.