NiMo Superalloy Additive Manufacturing for Reduced Chemical Segregation
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Solution Overview
Problem
Conventional methods of manufacturing molybdenum-containing superalloys, such as Haynes 242 alloy, using consumable electrode remelting processes like ESR and VAR, result in significant chemical segregation of heavy elements, leading to non-uniform microstructures and mechanical properties, which are undesirable for applications requiring uniform performance.
Innovation Solution
Utilizing additive manufacturing (AM) techniques with controlled, shallow melt pools to produce components, such as gas turbine parts, by selecting appropriate AM processes and materials, and programming specific process steps to minimize material segregation, particularly of molybdenum, through methods like laser or electron beam powder bed fusion or direct energy deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If consumable electrode remelting processes (ESR, VAR) are used to manufacture molybdenum-containing superalloys, then the manufacturing process is well-established and reliable, but significant chemical segregation of heavy elements occurs leading to non-uniform microstructures and mechanical properties
Solution Approach 1:
The invention changes the fundamental processing parameters by transitioning from consumable electrode remelting to additive manufacturing processes. This involves changing the heating method (from arc melting to laser/electron beam), the melting approach (from bulk remelting to layer-by-layer construction), and the thermal cycle characteristics. These parameter changes eliminate the chemical segregation inherent in traditional processes while achieving superior compositional uniformity.
Solution Approach 2:
The invention replaces the mechanical remelting process with an energy-based additive manufacturing system. Instead of using mechanical forces and conventional heat transfer, the patent employs focused energy fields (laser or electron beam) to melt and deposit material precisely where needed, substituting a mechanical-thermal system with an energy-field-based system that provides better control over material distribution and minimizes segregation.
2Manufacturing precision
If additive manufacturing techniques are used to produce components with controlled shallow melt pools, then material segregation is reduced and microstructure uniformity is improved, but the process complexity and programming requirements increase
Solution Approach 1:
The invention applies segmentation by dividing the component into thin layers and creating multiple shallow melt pools rather than one deep melt pool. This segmentation approach allows precise control over material deposition in each layer, reducing chemical segregation. The build process is broken down into discrete steps where each layer is independently controlled, enabling better material uniformity despite increased process steps.
Solution Approach 2:
The additive manufacturing process employs periodic action through repeated cycles of material deposition, melting, and solidification for each layer. This periodic process allows controlled cooling and solidification at each step, preventing the chemical segregation that occurs in continuous remelting processes. The rhythmic application of energy and material deposition creates uniform microstructures throughout the component.
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
AM techniques achieve components with reduced material segregation, resulting in more uniform microstructures and mechanical properties, enhancing the reliability and performance of parts like seals, retainer rings, and casings in gas turbines.
Implementation Method 1
additive manufacturing (AM) process steps that produce a plurality of shallow melt pools
Implementation Method 2
electron beam powder bed fusion
Implementation Method 3
building the component on the selected AM apparatus using the selected AM process steps
Data Source
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AI summary
A method of making a component using additive manufacturing (AM) techniques that selecting an AM manufacturing process suitable for making the component; selecting a material for the component that is compatible with the AM manufacturing component; selecting and programming AM process steps into a selected AM apparatus; and building the component on the selected AM apparatus using the selected AM process steps. The AM process steps are selected to produce a plurality of melt pools (32) that reduce material segregation in the finished part (30). The component exhibits reduced material segregation compared to making the material with a consumable electrode remelting process. The component made with AM techniques includes a region exhibiting reduced material segregation compared to making the material with a consumable electrode remelting process.