Aluminum Brazing Sheet Composition for High Strength Without Melting
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Solution Overview
Problem
Existing aluminum alloy brazing sheets face challenges in achieving high strength after brazing while preventing defects caused by melting during the brazing process, as higher contents of Si, Mg, and Cu can lower the solidus temperature, leading to melting issues.
Innovation Solution
The aluminum alloy brazing sheet is formulated with specific ranges of Si, Mn, and Mg contents, subjected to homogenization treatment, and structured as a multilayer with a core material and clad layers to maintain a high solidus temperature and enhance strength through precise chemical composition and processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If higher contents of Si, Mg, and Cu are added to achieve further higher strength, then strength after brazing is improved, but the solidus temperature of the core material becomes low and melting of members occurs during brazing
Solution Approach 1:
The invention changes the chemical composition parameters of the aluminum alloy by precisely controlling the content ranges of Si (0.2-1.0 mass%), Mn (0.1-0.8 mass%), and Mg (0.2-1.0 mass%), along with their interrelationships (Mn/Si ratio and Mg+Si sum). This parameter optimization allows the alloy to achieve high strength after brazing while maintaining an adequate solidus temperature to prevent melting during the brazing process.
2Strength
If Mg content is increased to improve strength after brazing, then yield strength is improved, but fluorine-based flux reacts with Mg to form inactive compounds and deteriorate brazing properties
Solution Approach 1:
The invention optimizes the Mg content parameter within a specific range (0.2-1.0 mass%) and establishes interrelationships with other elements (Mn/Si ratio of 0.10 or more and less than 1.00, and Mg+Si sum of 0.60 mass% or more and less than 1.60 mass%). This balanced composition allows the alloy to achieve high yield strength while limiting Mg content enough to prevent excessive reaction with fluorine-based flux, thereby maintaining good brazing properties.
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 achieves higher tensile strength and prevents defects like melting during brazing, ensuring improved strength and reliability of the aluminum alloy brazing sheets for heat exchangers.
Implementation Method 1
an ingot for the core material in which the Si content, the Mn content, and the Mg content are in the predetermined ranges and the relations among these contents are in the predetermined ranges is subjected to homogenization treatment at a predetermined temperature during a process for producing the aluminum alloy brazing sheet
Implementation Method 2
the strength is higher than strength of conventional aluminum alloy brazing sheets after artificial aging or room temperature aging is applied at specific retention temperature and retention time after brazing heating
Data Source
AI summary
An aluminum alloy brazing sheet has a core material of the aluminum alloy brazing sheet formed of an aluminum alloy comprising 0.20 mass % to 1.00 mass % of Si, 0.10 mass % to 0.80 mass % of Mn, and 0.20 mass % to 1.00 mass % of Mg, having a value of Mn content/Si content of 0.10 or more and less than 1.00, a value of Mg content+Si content of 0.60 mass % or more and less than 1.60 mass %, a Fe content of 0.40 mass % or less, a Cu content of 0.25 mass % or less, a Cr content of 0.10 mass % or less, a Zn content of 2.00 mass % or less, a Ti content of 0.10 mass % or less, and a Zr content of 0.10 mass % or less, with the balance being Al and inevitable impurities.