Recycled Aluminum Alloy Sheet Composition for DI Can Formability
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Solution Overview
Problem
There is a need for a process that produces an aluminum alloy sheet with sufficient strength and formability characteristics to be easily made into drawn and ironed beverage containers, while also enabling a majority of the melt composition to be derived from recycled aluminum containers.
Innovation Solution
The method involves producing an aluminum alloy sheet through a continuous casting process, where the alloy composition consists of specific ranges of manganese, magnesium, copper, iron, and silicon, and is derived largely from used beverage containers. This process includes hot rolling, hot mill annealing, intermediate annealing, and stabilize annealing to achieve desired physical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aluminum can recycling is increased to majority fraction of melt composition, then environmental impact is reduced and sustainability is improved, but the alloy composition control and manufacturing precision become more difficult
Solution Approach 1:
The patent applies parameter changes by precisely controlling the chemical composition parameters of the aluminum alloy, specifically maintaining Mn: 0.7-1.2%, Mg: 1.5-2.0%, Cu: 0.20-0.60%, Fe: 0.28-0.45%, Si: 0.10-0.30%. This compositional parameter control enables the use of recycled aluminum as the primary feedstock while ensuring the final alloy meets the required specifications for drawn and ironed container production
Solution Approach 2:
The patent implements feedback control through a systematic approach where recycled aluminum is melted and refined, then alloying elements are added to adjust the composition. The molten metal is continuously monitored and adjusted to maintain the target composition ranges, ensuring that despite variations in recycled material quality, the final product consistently meets specifications
2Productivity
If continuous casting process is used instead of ingot casting, then productivity is improved and manufacturing efficiency is increased, but the alloy formability and ease of manufacture may be compromised
Solution Approach 1:
The patent optimizes the alloy composition parameters specifically for continuous casting, adjusting the Mn and Mg content ranges to ensure proper solidification behavior and microstructure development during the continuous casting process, thereby maintaining formability while achieving high productivity
Solution Approach 2:
The patent applies preliminary action by carefully controlling the alloy composition before casting to pre-establish the conditions necessary for successful continuous casting and subsequent forming operations. The specific composition ranges are designed to ensure proper fluidity during casting and appropriate formability after rolling
3Strength
If aluminum alloy sheet is produced with higher strength characteristics, then container strength is improved, but the formability and ease of drawing and ironing operations are reduced
Solution Approach 1:
The patent achieves the optimal balance between strength and formability by precisely controlling the alloy composition parameters, particularly the Mn content (0.7-1.2%) which provides solid solution strengthening, and the Mg content (1.5-2.0%) which contributes to both strength and formability. This compositional optimization enables the alloy to exhibit adequate strength while maintaining the ductility required for drawing and ironing operations
Solution Approach 2:
The patent creates a composite aluminum alloy system that combines multiple alloying elements (Mn, Mg, Cu, Fe, Si) in specific proportions to achieve a synergistic effect where the combination provides both the required strength and formability that cannot be achieved with single-element additions
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 aluminum alloy sheet exhibits high strength, low earing, and excellent formability, making it suitable for producing drawn and ironed container bodies with reduced environmental impact through increased aluminum recycling levels.
Implementation Method 1
In a continuous casting process, molten metal is continuously cast directly into a relatively long thin slab
Implementation Method 2
the cast slab is then hot rolled and cold rolled to produce a finished product
Implementation Method 3
The strip is then cold rolled to the desired final gauge. The aluminum alloy composition and processing conditions are controlled to achieve desired physical properties including strength and formability
Data Source
AI summary
The present disclosure provides improved processes and compositions for continuously casting aluminum alloys. The resulting aluminum alloy sheet is useful for container body stock.