Magnesium Burn-off
Magnesium burn-off is the loss of magnesium during welding of aluminum alloys due to high arc temperatures. This leads to undercutting and increased stresses that can cause hot cracking.
Physikalisch-chemischer Wirkmechanismus
When welding aluminum alloys with magnesium, the high arc temperature oxidizes the metal. The magnesium reacts with oxygen and loses its chemical bond to the aluminum. This causes a loss of magnesium, known as burn-off.
Metallurgical Relevance & Welding Risks
The loss of magnesium can cause the aluminum to harden and lose its toughness. This increases stresses in the weld, which can lead to hot cracking. Additionally, burn-off can alter the metal's structure, affecting its mechanical properties.
Werkstattpraxis & Handlungsanweisungen
To minimize magnesium burn-off, it's important to carefully follow welding parameters like temperature and time. Use a suitable shielding layer or shielding gas (like argon) to protect the aluminum. For severe burn-off, post-treatment by heat treatment or chemical treatment may be needed to restore mechanical properties.