Oxygen deoxidation equilibrium
The oxygen deoxidation equilibrium determines the residual oxygen content in the weld metal through the chemical reaction of oxygen with deoxidizers such as aluminum or silicon.
Physico-Chemical Mechanism of Action
In molten steel, dissolved oxygen reacts with added deoxidizers such as aluminum or silicon. This prevents oxygen from entering the weld as porosity and damaging it.
Metallurgical Relevance & Risks in Welding
Too low a residual oxygen content leads to fine porosity and reduces the strength of the weld. Too high an oxygen content can cause hot cracks and glass-hard microstructures, which reduces toughness.
Workshop Practice & Instructions
Use deoxidizers like aluminum or silicon in the right ratio to the steel. Keep the weld pool at the correct temperature to achieve a stable oxygen-deoxidation balance. Monitor the residual oxygen content and adjust the deoxidation accordingly.