Aluminum Alloy Brazing Sheet Strength via Grain Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional aluminum alloy brazing sheets for heat exchangers in automobiles lack sufficient strength and brazing properties, particularly when reduced in thickness, which compromises their durability and longevity.
Innovation Solution
An aluminum alloy brazing sheet with specific alloy compositions and structures, including a core alloy with optimized Si, Fe, Cu, Mn, Mg, Ti, Zr, Cr, and V content, and a sacrificial anode material with controlled Zn content, combined with an Al-Si-based filler alloy, subjected to homogenization treatment and hot rolling processes to achieve a crystallized grain diameter of at least 100 µm, enhancing mechanical strength and brazing properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the thickness of aluminum alloy brazing sheet is reduced to decrease weight, then weight reduction is achieved, but strength after brazing deteriorates
Solution Approach 1:
The invention changes the chemical composition parameters of the aluminum alloy by precisely controlling the content ranges of Si (0.03-1.5 mass%), Fe (0.01-0.5 mass%), Cu (0.01-1.0 mass%), Mn (0.01-2.0 mass%), Mg (0.01-0.5 mass%), and other elements. This compositional optimization enables the material to achieve sufficient strength even at reduced thickness, resolving the contradiction between weight reduction and strength maintenance
Solution Approach 2:
The invention creates a composite microstructure through controlled precipitation of Mg2Si intermetallic compounds and specific grain size distribution (average crystallized grain diameter of 50-200 μm). This composite structure at the microlevel provides enhanced mechanical properties that compensate for the reduced overall thickness, allowing weight reduction while maintaining strength
2Stability of the object's composition
If homogenization treatment temperature is increased to improve alloy uniformity, then compositional homogeneity is improved, but premature precipitation of intermetallic compounds occurs reducing aging hardening effect
Solution Approach 1:
The invention optimizes the homogenization temperature parameter to a specific range (450-550°C) that is sufficiently high to achieve compositional uniformity but sufficiently low to prevent premature precipitation of Mg2Si intermetallic compounds. This precise parameter control allows the material to maintain both compositional homogeneity and aging hardening capability
Solution Approach 2:
The homogenization treatment is performed as a preliminary step before hot rolling and brazing, establishing uniform composition distribution in advance. This preliminary action ensures that subsequent aging treatment can effectively precipitate Mg2Si compounds for hardening without interference from compositional inhomogeneity, resolving the contradiction between uniformity and hardening effect
3Adaptability or versatility
If hot rolling temperature range is expanded to improve processing flexibility, then manufacturing adaptability is improved, but precipitation of harmful intermetallic compounds increases reducing strength after brazing
Solution Approach 1:
The invention defines a specific hot rolling temperature range (300-500°C) that provides sufficient processing flexibility for various manufacturing requirements while remaining below the threshold temperature that causes excessive precipitation of harmful intermetallic compounds. This optimized temperature parameter resolves the contradiction between processing flexibility and strength preservation
Solution Approach 2:
The invention converts the potential harmful effect of intermetallic compound precipitation into a beneficial outcome by carefully controlling hot rolling parameters. The controlled precipitation during hot rolling, when performed within the specified temperature range, actually contributes to the desired microstructure with appropriate grain size and controlled distribution of strengthening phases, rather than being purely detrimental
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 brazing sheet exhibits excellent brazing properties, high strength, and improved corrosion resistance, enabling the production of lightweight, efficient heat exchangers with extended lifespan.
Implementation Method 1
suitably regulating conditions for homogenization treatment of a core alloy
Implementation Method 2
by keeping the core alloy at the temperature of less than 500 °C before hot rolling
Implementation Method 3
an aging hardening effect based on Mg 2 Si
Implementation Method 4
brazing is conducted at a high temperature of about 600°C
Data Source
AI summary
An aluminum alloy brazing sheet having high strength comprising: a core alloy; an Al-Si-based filler alloy cladded on one side or both sides of the core alloy, wherein the core alloy is composed of an aluminum alloy containing 0.3-1.2% (mass%, the same applies the below) Si, 0.05-0.4% Fe, 0.3-1.2% Cu, 0.3-1.8% Mn, 0.05-0.6% Mg, and containing one or more elements selected from the group consisting of 0.02-0.3% Ti, 0.02-0.3% Zr, 0.02-0.3% Cr and 0.02-0.3% V, the balance of A1 and unavoidable impurities; and wherein, after the aluminum alloy brazing sheet is subjected to brazing, the core alloy features a metallic structure in which a density of intermetallic compounds having a grain diameter of at least 0.1 µm is at most ten grains per µm2.