Weldable Interlayers for Joining Non-Weldable Aluminum Alloys

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Solution Overview

Problem

Current methods for joining non-weldable aluminum alloys in aircraft fuselages, such as 2XXX and 7XXX alloys, are inefficient, often requiring riveting which is time-consuming, adds weight, and causes surface deformities, and existing solid-state welding techniques like ultrasonic, magnetic pulse, and friction stir joining have limitations including metallurgical effects and surface defects.

Innovation Solution

Building layers of weldable material on the surfaces of non-weldable materials using a solid state joining technique, followed by fusion welding at these layers to join the pieces, allowing for efficient and defect-minimized joining of thin components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If riveting is used to join non-weldable aluminum alloys, then the components can be connected, but the process is time-consuming, adds weight, and causes surface deformities

Engineering Contradiction:
Improvejoining speedVSAvoidtime-consuming process
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

A weldable aluminum alloy layer is deposited on the non-weldable aluminum alloy surface to act as an intermediary. This intermediate layer enables fusion welding between non-weldable components, eliminating the need for riveting and significantly reducing joining time while avoiding surface deformities and weight addition.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If ultrasonic joining is used, then continuous joining can be achieved, but it produces varying material properties and is limited to thin materials

Engineering Contradiction:
Improvecontinuous joining capabilityVSAvoidmaterial property consistency
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The invention changes the material parameter by depositing a weldable aluminum alloy layer on the non-weldable surface. This parameter change enables the use of fusion welding processes that provide more consistent material properties and greater control over the joining process, while still maintaining continuous joining capability.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If friction stir joining is used, then welding of non-weldable alloys is possible, but it requires direct contact and creates metallurgical effects

Engineering Contradiction:
Improvewelding capabilityVSAvoidmetallurgical effects and surface defects
Core Design Contradiction:
Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The weldable aluminum alloy layer serves as a mediator between the friction stir tool and the non-weldable substrate. This intermediate layer undergoes the metallurgical effects and surface defects during friction stir processing, protecting the base non-weldable alloy while still enabling the joining process to occur.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention converts the harmful metallurgical effects and surface defects into a beneficial outcome by confining them to the sacrificial weldable layer. This layer is specifically designed to withstand these effects while maintaining the integrity of the non-weldable base material, effectively using the harmful effects as a means to achieve successful joining.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

4Adaptability or versatility

If layers of weldable material are built up on non-weldable material, then fusion welding becomes possible, but additional processing steps are required

Engineering Contradiction:
Improvewelding applicabilityVSAvoidprocess complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The weldable aluminum alloy layer is deposited in advance on the non-weldable surface before the final joining operation. This preliminary action prepares the surface for fusion welding, enabling the use of versatile welding processes while the actual joining step remains relatively simple and straightforward.

Inventive Principle:
Principle #10Preliminary action

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 method enables quicker, more automated, and defect-reduced joining of high-performance aluminum alloys, optimizing the structure without damaging the materials, suitable for aircraft and other vehicle components.

Implementation Method 1

layers of a weldable material are built up on the surfaces of relatively thin pieces of non-weldable material using a solid state joining technique

Methodology Applied
Scientific EffectSolid state joining:

Implementation Method 2

the pieces are welded together at the layers of weldable material using a fusion welding technique

Methodology Applied
Scientific EffectFusion welding:

Data Source

PatentEP3366407B1Structure and method of making same involving welding otherwise non-weldable materials
Publication Date: 2023.05.24 SPIRIT AEROSYSTEMS INC
  • EP3366407B1 patent drawingFigure 1~2
  • EP3366407B1 patent drawingFigure 3~4
  • EP3366407B1 patent drawingFigure 5

AI summary

A structure (10,210) and a method of creating the structure (110,310) in which relatively thin pieces of non-weldable aluminum alloy (14,18, 214, 218) or other non-weldable material are welded together. First layers (22, 222) of a weldable material, such as a weldable aluminum alloy or other weldable material, having a total thickness of between 0,0254 and 0,762 cm [between 0.01 and 0.30 inches], are built up on a surface (28,228) of the first piece (12,212) using an ultrasonic or other solid state joining technique, and second layers (30,230) of the weldable material having a similar total thickness are built up on a surface of the second piece (16,216) using the same technique. The first piece (12, 212) is then welded to the second piece (16,216) at the first (22, 222) and second (30,230) layers of weldable material using a fusion welding technique. The resulting structure (10,210) may be part of an aircraft, landcraft, watercraft, or spacecraft type of vehicle or may be used in other high-performance applications.