Friction Stir Interlocking Dissimilar Materials Pin

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Solution Overview

Problem

Current methods for joining dissimilar metals with different melting points, such as steel and aluminum, face challenges in forming strong and resilient joints due to the formation of brittle intermetallic compounds, leading to costly and complex workarounds that often fail to provide acceptable solutions.

Innovation Solution

The method employs friction stir welding with a pin inserted through apertures in dissimilar materials, using friction stir welding to secure the pin in place, avoiding the central pin's welding to prevent intermetallic formation and utilizing thermally activated adhesive films to enhance joint strength and prevent galvanic corrosion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional welding is used to join dissimilar materials with different melting points, then joint strength can be achieved, but brittle intermetallic compounds form causing weld brittleness and failure

Engineering Contradiction:

Improvejoint strengthVSAvoidweld reliability

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The invention changes the welding parameters by using friction stir welding instead of conventional welding, operating in the solid state rather than melting the materials. This parameter change prevents intermetallic compound formation while maintaining joint strength, resolving the contradiction between strength and reliability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention replaces the thermal field of conventional welding with a mechanical field using friction stir welding. The mechanical stirring action joins dissimilar materials in the solid state without melting, eliminating intermetallic compound formation and thereby improving weld reliability while maintaining strength

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If temperatures are maintained low to prevent intermetallic compound formation, then weld brittleness is reduced, but joint strength decreases

Engineering Contradiction:

Improveweld reliabilityVSAvoidjoint strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The invention replaces thermal welding with mechanical friction stir welding, allowing strong joints to be formed at lower temperatures without intermetallic compound formation. The mechanical stirring action creates strong metallurgical bonds without the need for high temperatures, simultaneously achieving both reliability and strength

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If workarounds are used to eliminate brittle intermetallic portions, then weld reliability improves, but manufacturing complexity and cost increase

Engineering Contradiction:

Improveweld reliabilityVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts or eliminates the harmful intermetallic compound formation mechanism by using friction stir welding instead of conventional welding. By removing the melting step that causes intermetallic formation, the need for complex workarounds is eliminated, achieving both reliability and manufacturing simplicity

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces conventional welding with friction stir welding, fundamentally changing the joining mechanism to prevent intermetallic compound formation at the source. This substitution eliminates the need for additional steps to remove or manage intermetallics, reducing manufacturing complexity while maintaining reliability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 enables robust, cost-effective, and efficient joining of dissimilar materials like steel and aluminum, reducing the risk of galvanic corrosion and maintaining the integrity of non-metallic materials like carbon fiber composites, with improved joint strength and reduced heat input, suitable for various applications including automotive and construction.

Implementation Method 1

friction stir welding

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 2

friction stir welding a portion of the pin to a material adjacent said pin

Methodology Applied

Scientific EffectFriction heating: Viscous Heating

Data Source

PatentUS10369748B2Friction stirring interlocking of dissimilar materials

Publication Date: 2019.08.06 BATTELLE MEMORIAL INST

AI summary

A method for solid state joining of dissimilar materials using a friction stir welding device wherein a pin is inserted through an aperture defined in a first material and a second material to hold the materials together and then held in place by friction stir welding a portion of the pin to a material adjacent said pin, or by friction stir welding a cap or plug that holds the pin in place to the adjacent material. The result is a connection or join wherein the central portion of the pin is not friction stir welded but the portions holding the pin in place (the ends or caps) generally are.