Superalloy Forging Microstructure Control Below Eta Solvus
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Solution Overview
Problem
Hot forging of nickel-based superalloys often results in non-homogeneous microstructures due to forging temperature and forces, leading to excessive formation of grain boundary phases like delta and eta phases, which degrade mechanical properties such as ductility and creep resistance.
Innovation Solution
Controlling the temperature during forging by maintaining the substrate within a specific forging temperature range below the solvus temperature of grain boundary phases and using multiple die forging stages to refine grain size and control the formation of these phases, while quickly cooling the component to reduce precipitation and transformation of delta and eta phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If hot forging is used to form superalloy components, then the component can be shaped and formed, but the microstructure becomes non-homogeneous and grain boundary phases form excessively
Solution Approach 1:
The forging process is divided into multiple sequential stages with different dies, each stage progressively shaping the component while maintaining temperature control. This segmentation allows the material to be formed incrementally, reducing excessive grain boundary phase formation that would occur in a single-stage forging process.
Solution Approach 2:
The temperature parameter is strictly controlled within a specific range (below the solvus temperature) throughout the forging process. By maintaining the temperature within this optimized range, the process achieves both effective shaping and homogeneous microstructure formation, preventing excessive grain boundary phase precipitation.
2Shape
If forging temperature and forces are applied to change component shape, then the component can be formed, but grain boundary phases like delta and eta phases form excessively
Solution Approach 1:
The temperature is maintained below the solvus temperature throughout forging, which thermodynamically suppresses the formation of grain boundary phases while still allowing plastic deformation. This parameter control prevents the harmful phase formation that normally accompanies hot forging.
Solution Approach 2:
The substrate is heated to the optimal temperature range before forging begins, and this temperature is maintained throughout the entire multi-stage process. This preliminary temperature preparation ensures that the material remains in a state that resists grain boundary phase formation while being workable.
3Ease of manufacture
If the substrate is heated to forging temperature, then the material becomes workable, but grain boundary phases precipitate and degrade mechanical properties
Solution Approach 1:
The temperature is optimized to a specific range below the solvus temperature, which provides sufficient thermal energy for plastic deformation and workability while thermodynamically preventing the precipitation of grain boundary phases that would degrade mechanical properties.
Solution Approach 2:
The forging process uses multiple sequential stages with intermediate steps, allowing the material to be worked in increments while maintaining temperature control. This periodic action ensures continuous workability while preventing phase formation that would occur with prolonged exposure to higher temperatures.
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 approach results in a component with a uniform microstructure and a low volume fraction of grain boundary phases, enhancing mechanical properties like strength and ductility, particularly in regions subjected to higher stresses.
Implementation Method 1
a heat source configured to heat the substrate to within a forging temperature range and maintain the substrate within the forging temperature range during application of the plurality of die forging stages
Implementation Method 2
a cooling source configured to cool the component preform after completing the plurality of die forging stages
Data Source
AI summary
The disclosure describes example systems and techniques for controlling microstructure of a superalloy substrate by controlling temperature during forging and using multiple die forging stages to formation of grain boundary phases of the superalloy, and components formed by such example systems and techniques. The method includes heating a substrate to within a forging temperature range. The substrate includes a nickel-based superalloy, and the forging temperature range is below an eta phase solvus temperature of the substrate. The method includes applying a plurality of die forging stages to the substrate to form a component preform. The method includes maintaining the substrate within the forging temperature range during application of the plurality of die forging stages and cooling the component preform.