Oxygen Deoxidation by Aluminum
Aluminum binds dissolved oxygen in the melt to stable oxides, prevents porosity, and causes grain refinement. Too much aluminum can, however, lead to excessive fluidity.
Physicochemical Mechanism of Action
Aluminum reacts in the molten pool with dissolved oxygen to form stable aluminum oxides (Al2O3). This process prevents the formation of free oxygen, which would otherwise cause porosity.
Metallurgical Relevance & Risks in Welding
Deoxidation with aluminum improves weld quality by reducing porosity and also refines the grain. However, too high an aluminum content (above 0.1 %) can lead to excessive fluidity, which causes distortion and weak spots in the weld.
Workshop Practice & Action Instructions
Add aluminum in the filler material or as a flux. The optimal content is about 0.05 % to 0.1 %. Monitor the temperature and oxygen content in the melt to ensure effective deoxidation.