Al Alloy Strip Composition for Formability and Corrosion Resistance
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Solution Overview
Problem
Current aluminum alloys for motor vehicle components, such as interior door parts, face challenges in achieving a balance between high formability, medium strength, and corrosion resistance, particularly against filiform corrosion, while also being cost-effective and suitable for complex forming processes.
Innovation Solution
An aluminum alloy strip with specific composition proportions (Fe ≤ 0.80%, Si ≤ 0.50%, Mn 0.90% ≤ 1.50%, Mg ≤ 0.25%, Cu ≤ 0.20%, Cr ≤ 0.05%, Ti ≤ 0.05%, V ≤ 0.05%, Zr ≤ 0.05%, with a combined Mg and Cu ratio of 0.17% ≤ Mg + Cu ≤ 0.25%) that enhances yield strength, elongation, and corrosion resistance, allowing for use in complex forming processes and coated components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If alloy AA 8006 is used for high formability, then formability is improved, but susceptibility to filiform corrosion increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the chemical composition parameters of the aluminum alloy, specifically limiting Fe to ≤0.80%, Si to ≤0.50%, Mn to 0.90-1.50%, Mg to ≤0.25%, and Cu to ≤0.20%, with Mg+Cu combined ratio of 0.17-0.25%. This compositional parameter optimization resolves the contradiction by achieving both high formability (uniform elongation ≥23%, total elongation ≥30%) and corrosion resistance through balanced alloying elements that prevent filiform corrosion while maintaining ductility
Solution Approach 2:
The patent creates a composite alloy system by combining multiple alloying elements (Fe, Si, Mn, Mg, Cu, Cr, Ti, V, Zr) in specific proportions to achieve synergistic effects. The composite nature of this alloy composition provides both the formability characteristics of AA 8006 and the corrosion resistance typically associated with other alloy types, eliminating the need for continuous annealing processes
2Strength
If AA 6xxx alloys are used for high strength and corrosion resistance, then strength and corrosion resistance are improved, but formability deteriorates and production complexity increases
Solution Approach 1:
The patent achieves medium strength (yield strength ≥45 MPa) with high formability by changing the alloy composition parameters to an AA 3xxx series base with controlled additions of Mg (≤0.25%) and Cu (≤0.20%). This parameter optimization allows the material to achieve sufficient strength for motor vehicle components while maintaining uniform elongation ≥23% and total elongation ≥30%, avoiding the formability issues of AA 6xxx alloys
Solution Approach 2:
The patent extracts the continuous annealing process step from the production sequence by designing an alloy composition that achieves the desired mechanical properties through controlled rolling and standard heat treatment alone. This eliminates the complex and expensive continuous annealing step required by AA 6xxx alloys, reducing production complexity while maintaining yield strength ≥45 MPa
3Strength
If Mg and Cu content are increased to enhance strength, then yield strength is improved, but ductility and formability deteriorate
Solution Approach 1:
The patent optimizes the parameters of Mg and Cu content to achieve the ideal balance between strength and ductility. By limiting Mg to ≤0.25%, Cu to ≤0.20%, and maintaining their combined ratio Mg+Cu between 0.17-0.25%, the alloy achieves yield strength ≥45 MPa while preserving high ductility with uniform elongation ≥23% and total elongation ≥30%. This precise parameter control prevents the embrittlement that occurs with higher Mg and Cu content
Data Source
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AI summary
An aluminum alloy comprises 0.8 wt.% or less iron, 0.5 wt.% or less silicon, 0.9-1.5 wt.% manganese, 0.25 wt.% or less magnesium, 0.125 wt.% or less copper, 0.05 wt.% or less chromium, 0.05 wt.% or less titanium, 0.05 wt.% or less titanium, 0.05 wt.% or less zirconium, and remainder of aluminum and unavoidable elements at less than 0.05 wt.% individually and less than 0.15 wt.% in total. The total content of magnesium and copper is 0.15-0.25 wt.%. The proportion of magnesium in the aluminum alloy is more than the proportion of copper in the aluminum alloy. Independent claims are included for the following: (1) preparation of aluminum alloy strip; and (2) aluminum alloy strip.