Aluminum Alloy Brazing Sheet with Lamellar Grain Structure
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Solution Overview
Problem
Existing aluminum alloy brazing sheets face challenges in achieving both high strength and high elongation simultaneously, as increasing strength often impairs elongation characteristics, and vice versa, particularly in heat exchanger applications where thin-wall, high-strength, and corrosion-resistant materials are required.
Innovation Solution
An aluminum alloy brazing sheet with a core material and sacrificial material composition optimized for high strength and corrosion resistance, where the core material has a lamellar crystal grain structure, specific element content (Mn, Si, Fe, Cu), and the sacrificial material has a high Zn content, ensuring a balanced deformability and enhanced elongation and corrosion resistance post-brazing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the amount of Cu in core material is increased to achieve high strength, then tensile strength is improved, but deformability of core material becomes higher than sacrificial material resulting in reduced elongation
Solution Approach 1:
The patent optimizes the Cu content in core material to 0.7-1.3% and Zn content in sacrificial material to 4.0-8.0%, creating a balanced deformability relationship where the sacrificial material has slightly higher or equal deformability to the core material. This parameter optimization resolves the contradiction by preventing excessive strength increase that would imbalance the deformability between layers.
Solution Approach 2:
The patent uses a composite structure with core material containing specific alloying elements (Mn: 1.3-2.0%, Si: 0.6-1.3%, Fe: 0.1-0.5%, Cu: 0.7-1.3%) and sacrificial material with high Zn content (4.0-8.0%). The composite design ensures both materials have compatible deformability characteristics while achieving high strength and elongation simultaneously.
2Reliability
If the amount of Zn in sacrificial material is increased to improve corrosion resistance, then corrosion resistance is improved, but deformability of sacrificial material becomes higher than core material resulting in reduced elongation
Solution Approach 1:
The patent optimizes Zn content in sacrificial material to 4.0-8.0%, which provides sufficient corrosion resistance while maintaining deformability balance with the core material. This parameter control prevents excessive Zn addition that would create deformability imbalance between the sacrificial and core materials.
Solution Approach 2:
The composite material design combines sacrificial material with high Zn content (4.0-8.0%) and core material with specific alloy composition (Mn: 1.3-2.0%, Si: 0.6-1.3%, Fe: 0.1-0.5%, Cu: 0.7-1.3%). This composite structure achieves both high corrosion resistance and balanced deformability between layers.
3Weight of moving object
If thin-wall design is used to reduce weight and save space, then weight and space are reduced, but material strength and corrosion resistance requirements become more stringent
Solution Approach 1:
The patent employs a composite aluminum alloy brazing sheet with core material containing Mn (1.3-2.0%), Si (0.6-1.3%), Fe (0.1-0.5%), and Cu (0.7-1.3%), combined with sacrificial material containing high Zn (4.0-8.0%). This composite structure achieves high strength and corrosion resistance in thin-wall applications, enabling weight reduction while meeting performance requirements.
Solution Approach 2:
The patent applies different material compositions to different functional requirements: the core material is optimized for strength and formability with specific alloying elements, while the sacrificial material is optimized for corrosion resistance with high Zn content. This local quality differentiation enables thin-wall design to meet both weight reduction and performance requirements.
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 provides an aluminum alloy brazing sheet with high strength (tensile strength of 170 MPa or more), high elongation (4% or more), and improved corrosion resistance, suitable for heat exchanger applications by controlling the crystal grain size and second-phase particle distribution, thereby addressing the limitations of previous technologies.
Implementation Method 1
corrosion resistance can be improved by increasing the potential gap between the sacrificial material and the core material after brazing
Implementation Method 2
the other side of the core material being clad with an Al—Si-based or Al—Si—Zn-based brazing filler metal
Data Source
AI summary
An aluminum alloy brazing sheet has high strength, corrosion resistance and elongation, and includes an aluminum alloy clad material. The material includes a core material, one surface of which is clad with a sacrificial material and an other surface of which is clad with an Al—Si-based or Al—Si—Zn-based brazing filler metal. The core material has a composition containing 1.3 to 2.0% Mn, 0.6 to 1.3% Si, 0.1 to 0.5% Fe and 0.7 to 1.3% Cu, by mass, with the balance Al and impurities. The sacrificial material has a composition containing more than 4.0% to 8.0% Zn, 0.7 to 2.0% Mn, 0.3 to 1.0% Si, 0.3 to 1.0% Fe and 0.05 to 0.3% Ti, by mass, with the balance Al and impurities. At least the core material has a lamellar crystal grain structure. Elongation of material is at least 4% and a tensile strength after brazing is at least 170 MPa.