Aluminum Brazing Sheet Composition for Strength Without Mg Diffusion
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Solution Overview
Problem
Existing aluminum alloy brazing sheets face challenges in achieving both post-brazing strength and brazing property, particularly at the joint portions between the sacrificial material and the brazing filler material, due to the diffusion of Mg into the brazing filler during the brazing process, which reduces the brazing property and leads to potential failures.
Innovation Solution
A four-layer configuration aluminum alloy brazing sheet is developed, where the core material contains Si, Mn, Cu, and Mg, the sacrificial material includes Si and Zn, and the intermediate layer comprises Si and Mn, with specific composition ranges to enhance post-brazing strength and brazing property by regulating the Mn content in the sacrificial material and optimizing the fluidity of the molten brazing filler.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If Mg is added to the core material to improve strength, then post-brazing strength is improved, but Mg diffuses into the brazing filler material during brazing and reacts with flux, significantly reducing brazing property
Solution Approach 1:
An intermediate layer is introduced between the core material and the brazing filler material to prevent direct diffusion of Mg from the core material into the brazing filler material during the brazing process. This intermediate layer acts as a barrier that allows the strength-enhancing Mg content in the core material (0.05-0.80 mass%) to be maintained without causing brazing property degradation, thereby resolving the contradiction between improving post-brazing strength and maintaining reliable brazing properties.
2Strength
If the amount of Mg added to the core material is increased to further improve strength, then post-brazing strength continues to improve, but it becomes impossible to prevent decrease in brazing property even with the intermediate layer configuration
Solution Approach 1:
The invention optimizes the compositional parameters of the intermediate layer by specifying precise ranges for Si (0.10-1.50 mass%), Mn (0.05-2.00 mass%), and Cu (0.05-1.50 mass%). By controlling these compositional parameters within defined ranges, the intermediate layer effectively restricts Mg diffusion even when the core material contains higher Mg content (0.05-0.80 mass%), enabling simultaneous achievement of improved post-brazing strength and maintained brazing property.
3Strength
If Mn content in the sacrificial material is high, then strength is improved, but fluidity of molten brazing filler on the surface of sacrificial material deteriorates, reducing brazing property at joint portions
Solution Approach 1:
The invention optimizes the Mn content parameter in the sacrificial material by limiting it to 0.05-2.00 mass%, and more preferably 0.05-1.00 mass%. This parameter optimization ensures that the sacrificial material maintains adequate strength while preserving the fluidity of molten brazing filler on its surface during brazing, thereby preventing brazing failures at joint portions between the sacrificial material and brazing filler material.
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 solution effectively improves both post-brazing strength and brazing property, ensuring excellent joint integrity and preventing brazing failures by controlling the Mn content in the sacrificial material and optimizing the composition of the core and intermediate layers.
Implementation Method 1
Mg diffuses into the brazing filler material due to heating during brazing
Data Source
AI summary
An aluminum alloy brazing sheet including a core material, a sacrificial material provided on one surface of the core material, a brazing filler material provided on the other surface side of the core material, and an intermediate layer provided between the core material and the brazing filler material. The core material contains Si: 0.30 to 1.00 mass %, Mn: 0.50 to 2.00 mass %, Cu: 0.60 to 1.20 mass %, Mg: 0.05 to 0.80 mass %, and Al. The sacrificial material contains Si: 0.10 to 1.20 mass %, Zn: 2.00 to 7.00 mass %, Mn: 0.40 mass % or less, and Al. The intermediate layer contains Si: 0.05 to 1.20 mass %, Mn: 0.50 to 2.00 mass %, Cu: 0.10 to 1.20 mass %, and Al.