Aluminum-Zinc Stress Corrosion
Aluminum-zinc stress corrosion is electrochemical cracking under tensile stress in high-strength alloys such as Al-Zn-Mg-Cu. It occurs at grain boundaries and can be prevented by deliberate overaging (T7 temper).
Physical-Chemical Mechanism of Action
Aluminum-zinc stress corrosion occurs when high-strength alloys like Al-Zn-Mg-Cu are under tensile stress. Electrochemical processes at grain boundaries lead to cracking. This happens through zinc diffusion toward the aluminum direction and electrolysis of the zinc phase.
Metallurgical Relevance & Welding Risks
This corrosion can lead to cracking failure under tensile stress, especially in high-strength alloys. It is particularly dangerous in environments with high salt content or humidity. Cracks can spread quickly and severely affect the material.
Workshop Practice & Action Instructions
To avoid aluminum-zinc stress corrosion, deliberate overaging (T7 temper) is recommended. This condition increases strength and improves stress corrosion resistance. During welding, it is important to ensure a clean surface and correct welding parameters. Cooling temperature should be controlled to achieve a uniform grain structure.