Oxygen Affinity
Oxygen affinity is the thermodynamic tendency of a metal to react with oxygen and form stable oxides. In welding, this requires the use of deoxidizers to prevent porosity.
Physical-Chemical Mechanism of Action
Metals have a certain affinity for oxygen, determined by their chemical compounds and electronic structure. This affinity means metals tend to form oxides when oxygen is present.
Metallurgical Relevance & Risks in Welding
During welding, metals can react with oxygen released from the environment and form oxides. These oxides can get into the weld as porosity, compromising the strength and mechanical integrity of the joint. Therefore, it is crucial to use deoxidizers to prevent oxygen from reaching the metal.
Workshop Practice & Action Guidelines
To avoid porosity, the following measures are a must:
• Use deoxidizers like silicon or zinc before welding.
• Keep the metal away from oxygen during welding by welding in a closed system or using a protective gas atmosphere.
• Make sure all surfaces are clean and free of contaminants.