Intergranular Corrosion and Microstructural Evolution in a Newly Designed Al-6Mg Alloy.

Area of Science:

• Materials Science
• Corrosion Engineering
• Metallurgy

Background:

• Aluminum-magnesium (Al-Mg) alloys are widely used due to their good strength-to-weight ratio.
• Understanding their microstructure and corrosion behavior is crucial for optimizing performance in various applications.
• Intergranular corrosion (IGC) is a significant degradation mechanism in these alloys.

Purpose of the Study:

• To investigate the microstructure and intergranular corrosion behavior of a novel Al-6Mg alloy.
• To evaluate the effect of cold rolling reduction on alloy microstructure and IGC susceptibility.
• To identify key factors influencing the corrosion behavior of the studied Al-Mg alloy.

Main Methods:

• Al-6Mg alloy preparation via casting, homogenization, hot extrusion, and cold rolling (20% and 50% reduction).
• Microstructural analysis including grain size and intergranular misorientation measurement.
• Intergranular corrosion testing using a nitric acid mass-loss test (ASTM G67) after sensitization.

Main Results:

• The CR50 alloy (50% reduction) exhibited higher intergranular misorientation compared to the CR20 alloy (20% reduction).
• Average grain sizes were comparable: 19 ± 7 μm (CR20) and 17 ± 9 μm (CR50).
• CR20 alloy showed increased susceptibility to IGC with longer sensitization times, unlike CR50.

Conclusions:

• Grain size and beta (β) phase precipitation are critical factors affecting the IGC behavior of this Al-6Mg alloy system.
• Cold rolling reduction influences microstructural features like intergranular misorientation, impacting corrosion resistance.
• The study provides insights into tailoring Al-Mg alloy processing for enhanced corrosion performance.