Dual Microstructure Billet Inductive Heat Treatment
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Solution Overview
Problem
Current methods for forming dual microstructure components, such as turbine wheel hubs and rims, are inefficient and unsuitable for producing smaller-diameter components like those for auxiliary power units, as they often require multiple alloys and complex processing techniques, limiting production quality and efficiency.
Innovation Solution
A method involving the consolidation of powder material to form a billet with a first grain structure, followed by inductive heating above the gamma prime solvus temperature and subsequent subsolvus heat treatment to transform the grain structure, allowing the billet to be divided and machined into dual microstructure components with desired properties for hubs and rims.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional techniques (diffusion heat treatment, extrusion, or periphery heating) are used to form dual microstructure components, then high quality disks with dual properties can be produced, but only one disk may be produced at a time from each preform and the process is complex and expensive
Solution Approach 1:
The invention segments the heating process into two distinct stages: an austenitizing heat treatment to form a fine-grained microstructure, followed by a separate grain growth heat treatment to create a coarse-grained outer layer. This segmentation allows each microstructure type to be formed through optimized, independent processes, enabling high-quality dual microstructure components to be produced efficiently from a single preform without requiring complex multi-alloy construction or sequential production methods.
2Strength
If multiple alloys are joined by diffusion heat treatment or extrusion to create dual microstructure components, then high tensile strength and high stress rupture properties can be achieved, but the process becomes complex and relatively expensive
Solution Approach 1:
The invention applies local quality by creating different grain structures in different regions of the same alloy component through controlled heat treatments. The inner region undergoes austenitizing to achieve fine grains for high tensile strength, while the outer region undergoes grain growth treatment to achieve coarse grains for high stress rupture resistance. This eliminates the need for joining multiple alloys while achieving the desired dual mechanical properties through localized microstructural modification.
Solution Approach 2:
The invention utilizes parameter changes by varying heat treatment temperature and duration parameters to transform the microstructure of a single alloy. By controlling the heating rate, temperature profile, and holding time during the two-stage heat treatment process, the material transitions from a uniform fine-grained structure to a dual microstructure with fine-grained interior and coarse-grained exterior, achieving diverse mechanical properties without material composition changes.
3Manufacturing precision
If specialized equipment is used to heat the outer periphery of the disk preform to obtain a second grain microstructure, then dual microstructure properties can be achieved, but the equipment becomes complex and the process expensive
Solution Approach 1:
The invention implements continuity of useful action by applying heat treatments in a sequential, continuous manner where the first austenitizing heat treatment is immediately followed by the second grain growth heat treatment without interruption or repositioning of the component. This continuous processing approach eliminates the need for complex specialized equipment to selectively heat only the outer periphery, as the same heating system can progressively treat the entire component through controlled temperature profiles and timing.
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
This method enables the production of dual microstructure components with improved mechanical properties and increased efficiency, allowing for the production of multiple components simultaneously, reducing costs and complexity, and enabling the formation of smaller-diameter components like those for auxiliary power units.
Implementation Method 1
inductively heating the billet at an inductive heat treat temperature above a gamma prime solvus temperature of the alloy
Implementation Method 2
subjecting the billet to a subsolvus heat treat temperature that is below the gamma prime solvus temperature of the alloy
Data Source
AI summary
Methods of forming dual microstructure components include consolidating a powder material comprising an alloy to form a billet, the billet having a first grain structure, inductively heating the billet at an inductive heat treat temperature above a gamma prime solvus temperature of the alloy and subjecting the billet to a subsolvus heat treat temperature that is below the gamma prime solvus temperature of the alloy, waiting a period of time for the first grain structure in an outer portion of the billet to transform into a second grain structure that is coarser than the first grain structure, after the steps of inductively heating and subjecting the billet to the subsolvus heat treat temperature. The methods also include dividing the billet into at least two sections, and machining a final shape into one or more of the at least two sections to form the dual microstructure component.