Cold-Rolled 5xxx Aluminum Sheet for Glossy Anodized Surfaces
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Solution Overview
Problem
Existing methods for producing shiny parts from anodized 5xxx aluminum alloys fail to effectively reduce optical scattering centers, particularly Fe-containing precipitates, leading to reduced gloss and increased corrosion susceptibility.
Innovation Solution
Intermediate annealing between the solvus temperature of Mg-containing precipitates and the melting temperature of the aluminum alloy, followed by quenching before cold rolling, combined with high cold rolling degrees and final annealing, dissolves Mg-containing precipitates and fragments Fe-containing phases, enhancing gloss and corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If intermediate annealing is performed at temperature between solvus temperature of Mg-containing precipitates and melting temperature of aluminum alloy, then Mg-containing precipitates are dissolved and gloss is improved, but Fe-containing precipitates remain and cause corrosion susceptibility
Solution Approach 1:
The patent applies parameter changes by performing intermediate annealing at a specific temperature range (between solvus temperature of Mg-containing precipitates and melting temperature of aluminum alloy) to dissolve Mg-containing precipitates while preserving Fe-containing precipitates for subsequent fragmentation. This selective parameter control resolves the contradiction by targeting specific precipitate types at different processing stages.
Solution Approach 2:
The patent segments the treatment of different precipitate types by using intermediate annealing to address Mg-containing precipitates first, then applying high-degree cold rolling to fragment Fe-containing precipitates separately. This segmented approach allows each precipitate type to be treated optimally without compromising the other.
2Manufacturing precision
If high degree of cold rolling is applied to fragment Fe-containing precipitates, then gloss level is improved, but grain structure may coarsen and affect formability
Solution Approach 1:
The patent applies preliminary action by performing intermediate annealing before cold rolling to dissolve Mg-containing precipitates and prepare the matrix. This preliminary treatment facilitates subsequent high-degree cold rolling by reducing resistance to deformation, allowing Fe-containing precipitates to be fragmented effectively without excessive grain coarsening.
Solution Approach 2:
The patent maintains continuity of useful action by seamlessly connecting intermediate annealing with subsequent high-degree cold rolling without intermediate interruptions. This continuous process ensures that the benefits of precipitate dissolution are preserved while maximizing the fragmenting effect on Fe-containing precipitates during cold rolling.
3Stability of the object's composition
If intermediate annealing is performed to dissolve precipitates, then gloss stability is improved, but processing time and energy consumption increase
Solution Approach 1:
The patent optimizes processing time by carefully selecting the temperature range for intermediate annealing to achieve rapid dissolution of Mg-containing precipitates. By controlling the thermal parameters precisely, the process achieves the desired compositional stability efficiently, minimizing unnecessary time and energy expenditure.
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 method significantly improves the degree of gloss and durability by homogenizing precipitates, reducing scattering centers, and increasing corrosion resistance, resulting in a more stable and shiny surface.
Implementation Method 1
intermediate annealing with a first holding temperature T1 ≥ solvus temperature of Mg-containing precipitates
Implementation Method 2
subsequent cooling to room temperature
Implementation Method 3
subsequent cold rolling with a degree of cold rolling ≥ 70%
Data Source
AI summary
A process for producing a sheet or strip and a sheet or strip produced therein are described. For a comparatively high gloss level and comparatively high resistance, it is proposed that the sheet or strip, made of an aluminum alloy of type EN AW-5xxx, has a cold-rolled microstructure exhibiting a grain structure elongated in the rolling direction with grains whose grain size distribution ratio A1 = 11(0°)/11(90°) ≥ 10, in particular ≥ 15, as measured according to ASTM E112-13.