Aluminum Alloy Strip Composition for Brazed Heat Exchanger Strength
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Solution Overview
Problem
Existing aluminum alloys used in brazed heat exchangers face challenges in achieving a balance between improved corrosion resistance, mechanical strength, and brazability without increasing manufacturing costs, particularly due to varying silicon, copper, and magnesium contents.
Innovation Solution
A specific aluminum alloy composition with Si: 0.10-0.30%, Fe <0.25%, Cu: 0.85-1.1%, Mn: 1.2-1.7%, Mg: 0.1-0.3%, Ti: 0.05-0.20%, and optional Bi and/or Y, along with a manufacturing process involving casting, cladding, preheating, hot rolling, and annealing, enhances mechanical strength without degrading corrosion resistance or brazability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high Si content (0.8%) is used to compensate for absence of Cu and Mg for mechanical strength, then mechanical strength is improved, but corrosion resistance deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the Si content within 0.15-0.25% (deviating from conventional high Si content of 0.8%) and adjusting Cu to 0.9-1.0%, Mg to 0.1-0.21%, and Ti to 0.06-0.15%. This optimized composition range resolves the contradiction by achieving adequate mechanical strength without the excessive Si content that harms corrosion resistance.
Solution Approach 2:
The patent creates a composite alloy system combining multiple elements (Al-Si-Cu-Mg-Ti) where each element contributes specific properties. The synergistic interaction between these elements achieves both mechanical strength and corrosion resistance, with Ti specifically added to enhance corrosion resistance while Cu and Mg contribute to strength.
2Strength
If Cu amount is increased to improve mechanical strength, then strength is improved, but corrosion resistance may deteriorate
Solution Approach 1:
The patent optimizes Cu content to a precise range of 0.9-1.0%, avoiding both deficiency (which reduces strength) and excess (which harms corrosion resistance). This controlled parameter adjustment resolves the contradiction between strength and corrosion resistance.
Solution Approach 2:
The patent applies local quality by distributing different elements strategically: Cu (0.9-1.0%) provides localized strength enhancement, while Ti (0.06-0.15%) provides localized corrosion resistance enhancement, creating regions with optimized properties throughout the alloy structure.
3Strength
If Mg content is increased to improve mechanical strength, then strength is improved, but brazability deteriorates
Solution Approach 1:
The patent controls Mg content within 0.1-0.21%, a range that provides sufficient mechanical strength contribution while limiting the negative impact on brazability. This balanced parameter selection resolves the contradiction between strength and manufacturability.
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 new alloy composition and manufacturing process result in improved mechanical strength and corrosion resistance, allowing for thinner heat exchanger components with enhanced brazability, suitable for automotive applications.
Implementation Method 1
preheating up to a temperature from 450 to 520° C.
Implementation Method 2
annealing at a temperature from 240 to 450° C., preferably from 240 to 380° C., with holding at the maximum temperature for 10 minutes to 15 hours
Data Source
AI summary
A strip intended for the manufacture of brazed heat exchangers, having a core made of an alloy with the composition (weight %):Si: 0.10-0.30%, preferably 0.15-0.25%Fe<0.25%, preferably 0.1-0.2%Cu: 0.85-1.1%, preferably 0.9-1.0%Mn: 1.2-1.7%, preferably 1.2-1.4%Mg: 0.1-0.3%, preferably 0.1-0.21%Zn<0.1%Ti 0.05-0.20%, preferably 0.06-0.15%, more preferably 0.06-0.1%optionally up to 0.15% of Bi and/or Yother elements <0.05% each and <0.15% in total,remainder aluminium.