Superalloy Plug Brazing for Circular Cavity Repair
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Hard-to-weld and non-weldable alloys, such as nickel-based superalloys and certain aluminum-titanium alloys, pose challenges in repairing industrial machine parts due to their poor weldability, especially in components like turbine blades and nozzles with circular cross-sectional openings, leading to inefficient and lengthy repair cycles.
Innovation Solution
A method involving positioning a plug with an inner braze element into a cavity of the component, applying braze paste around the plug, and subjecting the component to a thermal cycle to form a metallurgical bond, completely sealing the cavity and ensuring proper repair without the limitations of conventional welding techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional welding techniques are used on superalloy components, then the repair process can be completed, but the poor weldability of HTW and NW alloys causes cracking, liquation, and repair failure
Solution Approach 1:
The patent replaces the welding process (mechanical/thermal joining method) with a brazing process. Instead of attempting to weld the superalloy components directly, which causes cracking and liquation, the invention uses a brazing alloy that melts at a lower temperature to join the components, avoiding the harmful effects of welding on HTW and NW alloys.
Solution Approach 2:
The patent changes the temperature parameters of the joining process. By using brazing temperatures (lower than welding temperatures) and controlling the thermal cycle, the process avoids the gamma prime phase transformation that causes cracking in superalloys. The controlled cooling rate also prevents liquation and ensures proper bond formation.
2Ease of operation
If plugs are inserted vertically for repair, then gravity helps insertion, but the plug may drop out during the process
Solution Approach 1:
The patent applies preliminary action by inserting the plug horizontally first, allowing it to be properly positioned and supported by the cavity walls before the brazing process begins. This preliminary positioning prevents the plug from dropping out during insertion, and the subsequent brazing permanently secures it in place.
3Reliability
If multiple braze cycles are used to ensure proper repair, then repair quality improves, but the repair cycle time becomes unacceptably long
Solution Approach 1:
The patent uses preliminary action by pre-positioning the plug horizontally and applying braze material before the brazing cycle begins. This preparation ensures that all components are in the correct position and the braze material is properly distributed, allowing a single braze cycle to complete the repair successfully without requiring multiple cycles for adjustments or rework.
Solution Approach 2:
The patent uses an intermediary substance (braze paste or braze material) that facilitates the joining process. This braze material acts as a mediator between the plug and the cavity walls, ensuring proper bonding in a single cycle by filling gaps and creating a reliable metallurgical bond without requiring multiple attempts.
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 effectively seals the cavity, ensuring a reliable and efficient repair process for superalloy components by forming a strong metallurgical bond, reducing the need for rework and shortening the repair cycle, while maintaining the superior properties of the superalloy materials.
Implementation Method 1
The component is subjected to a thermal cycle to melt the inner braze element around the plug, completely sealing the cavity by forming a metallurgical bond with the plug and the internal surface of the component
Implementation Method 2
positioning a plug having an inner braze element coupled thereto into a cavity defined by an internal surface of a component
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method for repairing a part and the resulting is disclosed. The method includes positioning a plug (50) having an inner braze element (52) coupled thereto into a cavity (46, 204) defined by an internal surface of a component (40). The cavity (46, 204) has a circular cross-section at the external surface (42) of the component (40). The plug (50) completely fills the circular cross-section and the inner braze element (52) is within the cavity (46, 204). A braze paste (56, 58) is positioned at least partially around the plug (50) at the external surface (42). The component (40) is positioned such that the inner braze element (52) is above the plug (50). The component (40) is subjected to a thermal cycle to melt the inner braze element (52) around the plug (50), completely sealing the cavity (46, 204) by forming a metallurgical bond (59, 66) with the plug (50) and the internal surface of the component (40). During the thermal cycle the braze paste (56, 58) is melted to form a metallurgical bond (59, 66) with the plug (50) and external surface (42).