Linear porosity
Pore chains are a series of gas pores aligned in a line parallel to the weld axis. They weaken the weld significantly along that line.
Physico-Chemical Working Mechanism
Pore chains form from gas bubbles joining together during the welding process. These bubbles can come from oxygen, hydrogen, or other gases and form long lines within the weld.
Metallurgical Relevance & Risks in Welding
Pore chains lead to a significant reduction in mechanical properties such as strength, toughness, and stress absorption in the affected zone. They can also serve as a source of cracks, especially under mechanical load or at temperatures near the melting point.
Shop Practice & Guidelines
To avoid pore chains, it is important to ensure a clean welding environment and a well-calibrated welding process. This includes:
• Thorough cleaning of the weld area before welding
• Using deoxidizers to prevent oxygen bubbles
• Controlled post-weld heat treatment to expel gas bubbles and stabilize the structure