Forming Gas Residual Oxygen Content
Trailing gas residual oxygen content is the oxygen content in ppm in the root shielding volume that determines the oxidation tendency during the welding process. It must be below specific limits before striking the arc to avoid discoloration and oxide films.
Physical-chemical mechanism of action
The residual oxygen content in the trailing gas affects the oxidation tendency of the root pass during the welding process. High oxygen content can lead to rapid oxidation and formation of discoloration.
Metallurgical relevance & risks in welding
Excessive residual oxygen can lead to the formation of discoloration and oxide films, which can damage the weld material. This can cause cracks and loss of strength. Additionally, it can lead to uneven thermal conductivity and irregular weld formation.
Shop practice & action instructions
Before striking the arc, the residual oxygen content in the trailing gas must be safely below the specific limits set for the material and welding process. This can be ensured by using high-quality trailing gas and proper gas supply.