Aluminium Alloy Header Sheet for Post-Braze Strength and Corrosion Resistance
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Solution Overview
Problem
Conventional aluminium alloy sheet materials used in heat exchangers lack sufficient post-braze strength, formability, and corrosion resistance, which are critical for applications in motor vehicles and HVAC&R components.
Innovation Solution
An aluminium alloy sheet material with a composition of Mn 1.4-1.8%, Si up to 0.7%, Fe up to 0.7%, Mg up to 0.30%, Cu up to 0.10%, Cr up to 0.25%, Zr up to 0.25%, Zn up to 0.50%, Ti up to 0.2%, and balance aluminium, manufactured using Direct-Chill casting or continuous casting techniques to achieve high post-braze yield strength and corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional aluminium alloy sheet materials are used in heat exchangers, then manufacturing and processing are straightforward, but post-braze strength is insufficient
Solution Approach 1:
The patent applies parameter changes by precisely controlling the chemical composition parameters of the aluminium alloy, specifically setting Mn content at 1.4-1.8%, Si at ≤0.7%, Fe at ≤0.7%, and other elements within specified ranges. This compositional parameter optimization enables the material to achieve post-braze yield strength ≥40 MPa and tensile strength ≥115 MPa, resolving the contradiction between ease of manufacture and joint reliability.
Solution Approach 2:
The patent creates a composite aluminium alloy material by combining multiple alloying elements (Mn, Si, Fe, Mg, Cu, Cr, Zn, Ti, Zr) in specific proportions to form a multi-element aluminium alloy system. This composite approach synergistically enhances post-braze strength while maintaining formability and corrosion resistance, addressing the reliability issue without sacrificing manufacturability.
2Strength
If aluminium alloy sheet material with high strength is used, then post-braze strength is improved, but formability deteriorates
Solution Approach 1:
The patent optimizes the alloy composition parameters to achieve a balance between strength and formability. By setting Mn at 1.4-1.8% (providing strength through precipitation hardening), Si at ≤0.7% (enhancing strength without excessive brittleness), and controlling other elements, the material achieves post-braze yield strength ≥40 MPa while maintaining adequate formability for heat exchanger manufacturing operations.
Solution Approach 2:
The patent applies local quality by creating different microstructural characteristics in different regions of the alloy through controlled composition. The specific element distribution and phases formed (such as Mn-rich precipitates) provide localized strengthening mechanisms that enhance post-braze strength while preserving overall ductility and formability required for manufacturing.
3Reliability
If conventional aluminium alloy is used, then manufacturing cost is low, but corrosion resistance is insufficient
Solution Approach 1:
The patent changes the compositional parameters by adding specific amounts of corrosion-resistant elements: Mn (1.4-1.8%) for galvanic corrosion protection, Cr (≤0.25%) and Ti (≤0.2%) for intergranular corrosion resistance, and Zn (≤0.50%) for overall corrosion enhancement. These parameter adjustments improve corrosion resistance while maintaining relatively simple manufacturing processes through Direct-Chill or continuous casting methods.
Solution Approach 2:
The patent develops a multi-element composite aluminium alloy that combines base aluminium with Mn, Si, Fe, Mg, Cu, Cr, Zn, Ti, and Zr in specific proportions. This composite material structure provides synergistic corrosion resistance mechanisms including galvanic protection, passive film formation, and intergranular stability, achieving superior corrosion protection without significantly complicating the manufacturing process.
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 aluminium alloy sheet material provides post-braze yield strength exceeding 40 MPa and tensile strength over 115 MPa, while maintaining good formability and corrosion resistance, preventing detrimental galvanic coupling and enhancing the performance of heat exchanger components.
Implementation Method 1
preventing detrimental galvanic coupling
Data Source
Figure 1
AI summary
The invention relates to a brazed heat exchanger comprises at least one header or manifold tube structured to hold a coolant; said header including a plurality of apertures; a plurality of substantially parallel fluid-carrying tubes each extending substantially perpendicular from one of said plurality of apertures in said header plate and structured to receive said coolant therethrough; and a plurality of corrugated aluminium alloy fins being in thermal communication with said plurality of fluid-carrying tubes and structured to transfer heat away therefrom, in order to cool said coolant as it circulates therein, and wherein said header is being made from the aluminium alloy sheet material comprising of, in wt.%: Mn 1.4%-1.8%, preferably 1.5%-1.8%; Si up to 0.7%; Fe up to 0.7%; Mg up to 0.30%; Cu up to 0.10%; Cr up to 0.25%; Zr up to 0.25%; Zn up to 0.50%; Ti up to 0.2%; balance aluminium and inevitable impurities.