Aluminum Weld Porosity
Aluminum weld porosity is caused by the rapid decrease in hydrogen solubility during the transition from liquid to solid. This leads to pore formation in the weld.
Physico-Chemical Mechanism of Action
Aluminum dealloys when it transitions from liquid to solid state. During this process, aluminum is highly soluble in hydrogen. After cooling, the solubility of hydrogen drops suddenly, causing rapid outgassing of hydrogen. This fast process can cause air bubbles and porosity in the weld.
Metallurgical Relevance & Welding Risks
Porosity in aluminum welds leads to weakened mechanical strength. It can also impair toughness and lead to cracking or deformation. Additionally, porosity can cause weld failure under mechanical stress.
Workshop Practice & Action Instructions
To avoid aluminum weld porosity, it's important to cool the weld as quickly as possible. This can be achieved by carefully selecting the welding process and shielding gas atmosphere. For TIG welding, use a high gas flow to accelerate cooling. Another trick is to use steel plates or other cooling aids right after welding to ensure uniform cooling.