Turbomachine Blade Friction Welding via Surfacing
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Solution Overview
Problem
Existing friction-welding methods for turbomachine blisks face challenges with significant variations in blade section, leading to height variations, localized strain, and heterogeneity in microstructure, especially when the thickness of the leading and trailing edges is small, causing thermal issues and weakening metallurgical bonding.
Innovation Solution
Surfacing the block's outer surface to create an enlarged welding area, machining for precision, and using fusion surfacing methods like laser or CMT welding to minimize heat-affected zones and ensure consistent flatness, followed by linear friction-welding with a preform blade positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If friction-welding is performed directly on the block without surfacing, then the process is simpler and faster, but the welding surface area is insufficient leading to localized strain and heterogeneity in microstructure
Solution Approach 1:
The block is pre-surfaced to create an enlarged welding surface before the friction-welding operation. This preliminary action of adding material to the block surface allows for a larger contact area during welding, distributing the thermal and mechanical loads more uniformly and preventing localized strain and microstructure heterogeneity.
2Strength
If the welding pressure is increased to improve bonding strength, then the metallurgical bonding is enhanced, but the heat-affected area increases causing thermal strain and material degradation
Solution Approach 1:
The surfacing material serves multiple functions: it enlarges the welding surface area to distribute pressure, and it acts as a sacrificial layer that melts and expels during friction-welding to create a cleaner weld interface. This multi-functionality allows the process to achieve strong bonding while managing heat effects.
Solution Approach 2:
The surfacing material is intentionally designed to be consumed during welding. The heat that would otherwise create excessive heat-affected areas in the original block is instead used to melt and expel the surfacing material, which acts as a protective sacrificial layer. This converts the harmful thermal effect into a beneficial cleaning and bonding process.
3Shape
If the block thickness at leading and trailing edges is reduced to achieve desired blade geometry, then the blade shape is improved, but the welding surface becomes too thin causing thermal issues and bonding weaknesses
Solution Approach 1:
The surfacing is applied specifically to the block surface at the leading and trailing edges where the thickness is reduced. This localized quality enhancement provides the necessary material thickness and surface area for reliable welding only in the critical regions, while maintaining the desired thin geometry elsewhere for proper blade shape.
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 enhances metallurgical bonding, reduces mechanical weaknesses, and minimizes heat-affected areas, resulting in a stronger and more consistent weld with improved microstructure homogeneity and reduced thermal strain.
Implementation Method 1
a fusion surfacing (refilling) by welding or laser
Implementation Method 2
a fusion surfacing (refilling) by welding or laser
Implementation Method 3
friction-welding the outer surface of the surfaced block and the blade
Implementation Method 4
the weld beads between the stops and the block are at least partially ejected in material flashes
Implementation Method 5
the electric current, confined in strictly localized contact points, will cause repeated sparkling (flash) and the expulsion of molten metal
Data Source
AI summary
According to the invention, a blade is friction-welded to a rotor disk of a turbomachine, the disk comprising a projecting block having an outer surface to which the blade is to be welded. To this end: a surfacing process is carried out on at least a part of the periphery of the block, in the region of said outer surface; the outer surface of the block and the surfacing are machined in order to level same; and friction-welding is then carried out between the surfaced outer surface of the block and the blade.