Dissimilar Metal Welding With Short-Wavelength Laser Filler Melting
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Solution Overview
Problem
When welding an iron-based metal member and an aluminum-based metal member using a filler material containing nickel and copper, the simultaneous heating of the aluminum-based metal member during near-infrared laser welding leads to the formation of a brittle intermetallic compound due to the mixing of melted aluminum and iron, which is exacerbated by unstable heat input and molten pool variations.
Innovation Solution
Using a short-wavelength laser light with a wavelength of 600 nm or less to melt a copper-based deposit metal member, which exhibits a high absorption rate for copper but low absorption for aluminum, thereby inhibiting the formation of brittle intermetallic compounds, and combining this with near-infrared laser light to maintain a stable molten state and enhance joint strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If near-infrared laser welding is used to melt the filler material, then the welding efficiency is improved, but the aluminum-based metal member is simultaneously heated and aluminum melts out, resulting in formation of brittle intermetallic compound
Solution Approach 1:
The patent segments the laser welding process into two distinct stages with different laser types: first using a green laser (532nm) to melt the filler material, then using a near-infrared laser (1070nm) to maintain the molten state. This segmentation allows each laser type to perform its optimal function without causing harmful effects, thereby resolving the contradiction between welding efficiency and prevention of intermetallic compound formation.
Solution Approach 2:
The green laser performs the preliminary action of melting the filler material before the near-infrared laser is activated. This preliminary melting action ensures that the filler material is fully melted and ready for joining, while preventing simultaneous heating of the aluminum-based metal member that would cause aluminum to melt out and form brittle intermetallic compounds.
2Speed
If high heat input is applied during welding, then the melting of filler material is accelerated, but the molten pool becomes unstable and aluminum mixes with iron, forming brittle intermetallic compound
Solution Approach 1:
The patent divides the heating process into two phases: the green laser provides controlled heat input for stable melting of the filler material, while the near-infrared laser maintains the molten state without causing excessive heat input. This segmentation prevents molten pool instability and aluminum-iron mixing while maintaining adequate melting speed.
Solution Approach 2:
The patent changes the laser wavelength parameter from near-infrared (1070nm) to green (532nm) during the melting phase to reduce heat input and stabilize the molten pool. This parameter change prevents excessive aluminum melting and intermetallic compound formation while maintaining sufficient melting speed through the combined action of both lasers.
3Device complexity
If conventional laser welding is used, then the process is simple, but brittle intermetallic compound forms at the joint portion
Solution Approach 1:
The patent segments the laser welding process into two distinct stages using different laser types, which increases device complexity but effectively prevents brittle intermetallic compound formation. The green laser melts the filler material while the near-infrared laser maintains the molten state, creating a controlled welding process that eliminates the harmful effects of conventional single-laser welding.
Solution Approach 2:
The patent employs a composite approach by combining two different laser types (green laser and near-infrared laser) in sequence, similar to using composite materials. This composite welding process leverages the advantages of each laser type while mitigating their individual disadvantages, preventing intermetallic compound formation while maintaining joint strength.
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
The method stabilizes the welding process, prevents the formation of brittle intermetallic compounds, and achieves a stronger joint between the iron-based and aluminum-based metal members by ensuring stable melting and spread of the deposit metal.
Implementation Method 1
The short-wavelength laser light tends to exhibit a high absorption rate for metals that are commonly used as the deposit metal member, but a low absorption rate for aluminum. Thus, with the configuration as described above, when the deposit metal member is melted using irradiation of the short-wavelength laser light
Implementation Method 2
a near-infrared laser light with a wavelength in a near-infrared region may be used, in addition to the short-wavelength laser light, as the laser light. With such a configuration, the deposit metal member is melted by the short-wavelength laser light, and a molten state of the deposit metal member is easily maintained by the near-infrared laser light
Implementation Method 3
the deposit metal member in the molten state easily spreads out on the respective joint surfaces of the iron-based metal member and the aluminum-based metal member
Data Source
AI summary
A method of manufacturing a joined body formed by welding using a deposit metal member includes irradiating the deposit metal member with a laser light to form a joint portion that joins an iron-based metal member and an aluminum-based metal member by the deposit metal member that is melted. The joint portion is formed so as to lie astride a first joint surface of the iron-based metal member and a second joint surface of the aluminum-based metal member. A short-wavelength laser light with a wavelength of 600 nm or less is used as the laser light.