Dissimilar Metal Flared Joint with Controlled Intermetallic Layer
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Solution Overview
Problem
Brazing fusion welding of dissimilar metal materials often results in a brittle intermetallic compound at the joint interface, reducing joining strength, and laser brazing faces challenges in applying heat uniformly, especially in forming high-strength flared joints.
Innovation Solution
A joined body of dissimilar metals is formed using a first metal member with a curved surface and a second metal member of higher melting point, where a filler material is irradiated with a laser to create a flared joint with an intermetallic compound thickness of 3 μm or less, and a melted and non-melted portion are formed in the thickness direction, with a joint length of 2 to 4 mm and a non-melted portion depth of 0.5 to 0.9 times the total depth, using a filler material like an aluminum alloy flux-cored wire.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If brazing fusion welding is used to join dissimilar metals, then the joining process can be completed, but a brittle intermetallic compound is formed at the joint interface which reduces joining strength
Solution Approach 1:
The patent applies parameter changes by precisely controlling laser power, welding speed, and filler material composition to limit intermetallic compound thickness to 3 μm or less. This quantitative control transforms the welding process from a粗放 (rough) operation to a precision process, resolving the contradiction between achieving joint formation and maintaining high strength
Solution Approach 2:
The patent creates local quality differences by forming a melted portion with specific depth (0.5 to 0.9 times the total depth) and controlling the intermetallic compound distribution locally at the joint interface. This localized control ensures high strength at the critical interface while maintaining overall joint integrity
2Manufacturing precision
If laser brazing is used to reduce intermetallic compound thickness, then the thickness can be decreased to 3 μm or less, but the heat input is smaller than arc welding requiring further studies for practical application
Solution Approach 1:
The patent introduces filler material as an intermediary substance that facilitates the joining process with lower heat input. The filler material acts as a mediator between the laser beam and the dissimilar metals, enabling controlled intermetallic compound formation while maintaining practical applicability for automotive structures
Solution Approach 2:
The patent changes multiple parameters simultaneously - laser power, welding speed, filler material composition, and joint geometry (flared joint with specific curvature) - to create optimal conditions for practical laser brazing application with controlled heat input and high joining strength
3Shape
If flared joint is used for joining dissimilar metals, then the appearance can be improved, but it is difficult to form a melted portion and obtain strength at the joining portion while suppressing intermetallic compound generation
Solution Approach 1:
The patent creates a composite structure at the joint interface consisting of the first metal member, filler material, and second metal member with controlled intermetallic compound layer. This composite structure maintains the flared joint's aesthetic appearance while ensuring high strength through optimized material composition and interface control
Solution Approach 2:
The patent applies local quality control by creating a specific melted portion depth (0.5 to 0.9 times the total depth) and controlling intermetallic compound formation only at the interface region. This localized treatment preserves the overall flared joint shape while ensuring strength at the critical joining portion
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 achieves a high joining strength for flared joints in dissimilar metals by controlling the intermetallic compound thickness and joint geometry, enhancing tensile strength and preventing mechanical strength reduction in the first metal member.
Implementation Method 1
a joining metal portion formed by irradiating a filler material and the first metal member with a laser
Implementation Method 2
in the curved surface portion of the first metal member on which the flared joint is formed, a melted portion and a non-melted portion are formed
Data Source
AI summary
A joined body of dissimilar metals, in which a flared joint is formed and which have a high joint strength, is provided. The joined body contains a first metal member having a curved surface portion, a second metal member having a higher melting point than the first metal member and joined to the first metal member to form the flared joint, and a joining metal portion formed by irradiating the first metal member and a filler material disposed between the first and second metal members with a laser. An intermetallic compound formed at the interface between the second metal member and the joining metal portion has a thickness of at most 3 μm. A melted portion and a non-melted portion are formed in the curved surface portion of the first metal member in which the flared joint is formed.