Pore chain
A gas pocket chain is a series of interconnected pores along the weld seam that leads to high stress and can cause cracks.
Physicochemical mechanism of action
A gas pocket chain forms when several smaller pores merge into a long, interconnected line. This often occurs through diffusion processes and the attraction of gas molecules to the weld seam.
Metallurgical relevance & risks in welding
Gas pocket chains lead to increased local stress concentration, putting the structure under pressure. This can cause cracks and deformation of the weld, especially if the pores are filled with carbon or other gases. The risk is particularly high at elevated temperatures and poor shielding gas conditions.
Workshop practice & instructions
To avoid gas pocket chains, you should:
• Use a high-quality shielding gas mixture (e.g., 98% argon + 2% CO2)
• Cool the weld as quickly as possible
• For heavy metals, perform a thorough grain refinement before welding
• Ensure shielding gas coverage throughout the entire welding time