5000 Series Aluminum Sheet Mg Control for Streak-Free Anodizing
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Solution Overview
Problem
Aluminum alloy sheets used in automotive and consumer electronics often exhibit a band-like streak pattern after anodizing, which compromises their surface quality, despite previous methods controlling chemical components and crystal grain size.
Innovation Solution
A method involving hot rolling and cold rolling of aluminum alloy sheets with controlled Mg concentration, where the difference in Mg concentration between areas within crystal grains is maintained at 0.80 mass% or less, and homogenization is performed at temperatures below the solidus temperature for over 3 hours, to prevent streak patterns during anodizing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods control chemical components and crystal grain size, then manufacturing precision is improved, but streak pattern prevention is insufficient
Solution Approach 1:
The invention changes the parameter of Mg concentration distribution within crystal grains, specifically controlling the difference in Mg concentration between the center area and areas away from grain boundaries to be 0.80 mass% or less. This parameter change in compositional distribution resolves the contradiction by providing a specific control criterion that ensures both manufacturing precision and reliable streak pattern prevention during anodizing
Solution Approach 2:
The invention applies local quality control by specifying different Mg concentration requirements for different regions within crystal grains. The center area and areas away from grain boundaries are treated differently, with the concentration difference between these regions being controlled to prevent streak patterns, while maintaining overall compositional control
2Stability of the object's composition
If homogenization is performed at high temperature for long duration, then concentration uniformity is improved, but production time and energy consumption increase
Solution Approach 1:
The invention changes the homogenization parameters by specifying a temperature range of solidus temperature-100°C to solidus temperature-50°C and a time period of more than 3 hours. This optimized parameter combination achieves the required Mg concentration uniformity (difference of 0.80 mass% or less) while balancing production time and energy consumption, resolving the contradiction between composition stability and time loss
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 produces aluminum alloy sheets with excellent surface quality after anodizing, as the controlled Mg concentration prevents band-like streak patterns, ensuring a uniform anodic oxide coating and improved strength without visible streaks.
Implementation Method 1
an aluminum alloy sheet that comprises a peritectic element (preferably Ti, Cr) that undergoes a peritectic reaction with aluminum
Implementation Method 2
the state of Mg that is present in a solid-solution state in an aluminum alloy that includes Mg that undergoes a eutectic reaction with aluminum
Implementation Method 3
homogenization is performed at a temperature equal to or higher than a temperature less than 'solidus temperature-50°C' for more than 3 hours
Implementation Method 4
an aluminum alloy sheet that exhibits excellent surface quality after anodizing
Data Source
AI summary
An aluminum alloy sheet exhibits excellent surface quality after anodizing without showing a band-like streak pattern. The aluminum alloy sheet is a 5000 series aluminum alloy sheet that includes 1.0 to 6.0 mass% of Mg, wherein the concentration of Mg in a solid-solution state that is present in an outermost surface area of the aluminum alloy sheet varies in the widthwise direction of the aluminum alloy sheet in the form of a band having a width of 0.05 mm or more, and the difference in the concentration of Mg between adjacent bands is 0.20 mass% or less.