Gradient Weld Filler for Gas Turbine Diaphragm Crack Resistance
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Solution Overview
Problem
Gas turbine components, particularly diaphragms, face challenges in withstanding thermally, mechanically, and chemically hostile environments, leading to issues such as cracking in welds and interfaces, which limits their operational temperature and efficiency.
Innovation Solution
A method involving multiple layers of filler materials with specific compositions and thermal expansion coefficients is applied to gas turbine components to create a weld without cracks, where the first layer has a lower thermal expansion coefficient than the base metal and higher yield strength, and the second layer has a higher thermal expansion coefficient and yield strength than the first layer, optimizing the component's properties for higher temperature operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional welding is used to join gas turbine components, then the component can be assembled and operated, but cracks occur in the weld and interface due to thermal expansion mismatch and stress concentration
Solution Approach 1:
The patent applies local quality by creating a gradient filler composition that varies locally from the base metal into the weld. The filler material composition changes continuously, with carbon content decreasing and nickel content increasing from the base metal side toward the weld center, creating localized property variations that reduce stress concentration and prevent cracking at the weld interface.
Solution Approach 2:
The patent employs parameter changes by systematically varying the chemical composition parameters of the filler material. The filler contains carbon (0.05-1.0%), silicon (0.1-0.5%), manganese (0.1-0.5%), and nickel (89.0-99.85%), with the composition creating a gradient that changes thermal expansion and mechanical properties to match between base metal and weld, eliminating the harmful thermal stress mismatch.
2Strength
If the filler material has the same thermal expansion coefficient as the base metal, then thermal stress is minimized, but the weld lacks the necessary strength and crack resistance for high-temperature operation
Solution Approach 1:
The patent uses composite materials by creating a weld that is a composite of base metal and filler material with a gradient composition. This composite structure combines the high strength of nickel-based alloys with the controlled thermal expansion properties, enabling the weld to withstand both mechanical loads and thermal stresses at elevated temperatures up to 1000°F (538°C) or higher.
Solution Approach 2:
The patent explicitly addresses thermal expansion by designing the filler composition to have thermal expansion properties that bridge the gap between base metal and weld metal. The gradient composition ensures compatible thermal expansion behavior across the weld interface, preventing crack formation during thermal cycling while maintaining the high-temperature strength required for gas turbine operation.
3Ease of manufacture
If a single-layer filler is used for welding, then the welding process is simple and fast, but the weld cannot accommodate the differential thermal expansion between base metal and surrounding components
Solution Approach 1:
The patent applies parameter changes by defining specific compositional parameters for the filler material that create a gradient structure. The filler contains carbon (0.05-1.0%), silicon (0.1-0.5%), manganese (0.1-0.5%), and nickel (89.0-99.85%), with the composition varying from the base metal interface toward the weld center. This compositional gradient accommodates thermal expansion differences while maintaining manufacturing simplicity through a single-pass welding 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 method effectively prevents cracking in welds and interfaces, enabling gas turbine components to operate at higher temperatures with improved efficiency and reliability.
Implementation Method 1
The first filler thermal expansion coefficient is less than both the base metal thermal expansion coefficient and the second filler thermal expansion coefficient
Implementation Method 2
The first filler yield strength is greater than the base metal yield strength and less than the second filler yield strength. The first filler elongation is greater than the base metal elongation and less than the second filler elongation
Data Source
Figure 1
AI summary
A component (100) and a method of processing a component are disclosed. The method includes providing a base metal (102) having a feature, removing the feature to form a processed region, applying a first layer (104) to the processed region, and applying a second layer (106) to the first layer. The base metal (102), the first layer (104), and the second layer (106) each have predetermined thermal expansion coefficients, yield strengths, and elongations. The processed component (100) includes the first layer (104) applied to a processed region of the base metal and a second layer (106) applied to the first layer (104).