One-Piece Cast Turbine Transition Piece for Joint-Free Strength
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Solution Overview
Problem
Existing gas turbine transition pieces face challenges with material properties mismatch at joints due to welding or brazing, leading to reduced low cycle fatigue, creep strength, and increased manufacturing complexity, especially in high-temperature applications where thin-walled cast objects often cool too quickly, resulting in undesirable properties.
Innovation Solution
A one-piece cast transition piece formed from nickel-based or cobalt-based superalloys like UDIMET 500, using a temperature-controlled casting process, which eliminates the need for mechanical connections and provides enhanced mechanical properties, reduced machining requirements, and improved manufacturability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If multiple cast pieces are joined by welding or brazing to form turbine combustor components, then the components can be assembled from separate parts, but the joint locations have material properties that do not match the remainder of the components, reducing low cycle fatigue and creep strength
Solution Approach 1:
The patent merges multiple separate cast pieces into a single integrated casting. The transition piece is formed as one continuous component with the combustion chamber and turbine nozzle assembly, eliminating the need for welding or brazing joints. This integration ensures uniform material properties throughout the entire assembly, resolving the strength mismatch issue at joint locations.
Solution Approach 2:
The patent segments the transition piece into a one-piece casting that integrates multiple functional zones (combustion chamber, transition section, turbine nozzle support) without requiring separate components. This segmentation approach allows the entire assembly to be manufactured as a single unit, avoiding weak joints while maintaining manufacturing feasibility through specialized casting processes.
2Weight of moving object
If thin-walled cast objects are produced, then the component weight and material usage are reduced, but the molten material cools too quickly in the mold, resulting in undesirable properties for hot gas path parts
Solution Approach 1:
The patent changes the thermal parameters during the casting process by implementing controlled cooling rates. The casting process maintains elevated temperatures during solidification and employs post-casting heat treatment to achieve the desired microstructure and material properties. This allows thin-walled construction while preventing excessive cooling that would degrade material performance.
Solution Approach 2:
The patent utilizes controlled phase transitions of the molten metal during casting. By managing the solidification process and employing heat treatment operations, the material undergoes controlled phase changes that develop the required microstructure and mechanical properties in thin-walled sections, preventing detrimental rapid cooling effects.
3Ease of manufacture
If traditional casting methods are used for large cast objects with thin walls, then manufacturing is simplified, but the molten material cools too quickly resulting in products that do not have desirable properties for hot gas path parts
Solution Approach 1:
The patent applies preliminary heating and temperature control measures during the casting process. The mold and casting environment are pre-heated to maintain appropriate temperatures during solidification, preventing rapid cooling of thin-walled sections. This preliminary thermal preparation ensures that the material develops the required properties while maintaining the simplicity of the casting manufacturing process.
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 one-piece cast transition piece extends component life, reduces production costs and time, and enhances strength and integrity by ensuring consistent material properties throughout, eliminating weaker joints and improving resistance to low cycle fatigue and creep.
Implementation Method 1
temperature-controlled casting process
Data Source
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AI summary
A combustion system including a transition piece (44) and method of forming the transition piece (44) using a cast nickel-based superalloy is provided. The transition piece (44) includes a body (68) defining a flowpath (72) and enclosure (70), the body (68) having a circular inlet section (60) for receiving combustion product from the combustor (40) and an outlet end (62) for flowing the combustor products into a first stage nozzle of a gas turbine. The transition piece (44) comprises a one-piece single casting construction of the circular inlet section (60), the body (68), and the outlet end (62). The transition piece (44) is formed from a nickel-based superalloy. The transition piece has a thick-to-thin ratio of wall thickness (84) of thick transition (80) to wall thickness (84) of thin transition (82) of about 1.1 to about 2.5.