Oxygen activity in liquid metal
Oxygen activity in liquid metal determines the thermodynamic solution potential of free oxygen in the melt and allows targeted deoxidation interventions.
Physical-Chemical Mechanism of Action
Oxygen activity in the molten metal describes how much free oxygen is dissolved in the weld pool. It affects the thermodynamic equilibrium and reactions between the metal and other substances.
Metallurgical Relevance & Risks in Welding
High oxygen activity can lead to porosity because oxygen reacts with carbon to form gas. This can impair the strength and mechanical properties of the weld. Therefore, controlled oxygen activity is crucial for a high-quality weld.
Workshop Practice & Instructions
To control oxygen activity in the molten metal, silicon or other deoxidation agents are often used. A typical silicon content is about 0.40 % combined with carbon. This prevents porosity and improves weld toughness.