Aluminum Brazing Fin Sheet for Strength-Ductility Balance
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Solution Overview
Problem
Existing fin materials for heat exchangers face a tradeoff between strength and ductility, making it difficult to achieve both high strength and excellent ductility while maintaining a compact design.
Innovation Solution
A brazing sheet composed of a core material with specific chemical composition and crystalline-aggregate structure, combined with filler materials, is manufactured through a controlled process involving casting, layering, hot-rolling, annealing, and cold-rolling to enhance both strength and ductility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the fin material is made thinner to reduce heat exchanger size, then the heat exchanger becomes more compact, but the strength of the fin material decreases
Solution Approach 1:
The patent uses a composite structure consisting of a core material layer and filler material layers. The core material provides structural strength while the filler materials (with 5-15 mass% Si and 0.05-0.8 mass% Fe) enhance brazeability and strength. This layered composite structure allows thin fin materials to maintain high strength through the synergistic combination of different material properties.
Solution Approach 2:
The patent optimizes chemical composition parameters (Si: 5-15 mass%, Fe: 0.05-0.8 mass%, Mn: 0.8-2.0 mass%) and metallurgical structure parameters (crystal grain size, phase distribution) of the core material to achieve high strength in thin sections. By precisely controlling these parameters, the fin material maintains superior strength even at reduced thickness.
2Ease of operation
If ductility is improved to enable complex shaping, then the fin material becomes easier to form into slits and louvers, but strength tends to decrease
Solution Approach 1:
The patent creates different material properties in different layers: the core material layer is optimized for ductility and formability to enable complex shaping into slits and louvers, while the filler material layers are optimized for strength and brazeability. This local differentiation of material properties allows the fin material to be easily formed into complex shapes while maintaining high strength in the final product.
Solution Approach 2:
The layered composite structure allows the core material to provide ductility for forming operations while the filler materials provide strength. The core material's metallurgical structure (controlled crystal grain size and phase distribution) enables excellent formability, and after forming, the filler materials contribute to high strength in the finished heat exchanger components.
3Productivity
If the fin material is made thinner to improve heat exchange efficiency, then the heat exchanger becomes more efficient, but the brazeability deteriorates
Solution Approach 1:
The patent uses a composite structure where filler material layers containing 5-15 mass% Si and 0.05-0.8 mass% Fe are applied on both surfaces of the core material. These filler materials specifically enhance brazeability by forming low-melting-point eutectic structures with the core material, enabling reliable brazing joints even in thin fin materials used for high-efficiency heat exchange.
Solution Approach 2:
The patent optimizes the chemical composition parameters of the filler materials (Si: 5-15 mass%, Fe: 0.05-0.8 mass%) to achieve optimal brazeability. By controlling these compositional parameters, the fin material maintains excellent brazing performance even when reduced to thin sections required for high heat exchange efficiency.
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 resulting fin material exhibits improved strength and ductility, allowing for easier deformation and maintaining shape after forming, while also enhancing brazeability and corrosion resistance.
Implementation Method 1
a total amount of diffusion M calculated according to Equation (1) below becomes 1.0×10−14 m2 or more and 5.0×10−12 m2 or less
Implementation Method 2
an annealing process, in which the clad sheet after the first cold-rolling process is annealed by heating it
Data Source
AI summary
An aluminum-alloy, fin material is composed of a brazing sheet containing a core material and filler material(s) disposed on both sides of the core material. The core material is an aluminum alloy containing 0.02-0.80 mass % Si, 0.02-0.80 mass % Fe, and 0.8-2.0 mass % Mn. The core material has a crystalline-aggregate structure in which: the orientation density of one or more of brass orientation, copper orientation, and S orientation is 20 times or more that or those of a randomly oriented sample; and the orientation densities of cube orientation, CR orientation, and P orientation are each 10 times or less than those of the randomly oriented sample. The filler material(s) is (are) composed of an Al—Si series alloy that contains 6.0-13.0 mass % Si and 0.02-0.80 mass % Fe. The clad percentage of filler material(s) is 6-16% of the total thickness of the brazing sheet.