Cluster porosity
A porosity cluster is a dense accumulation of pores in a small area of the weld. It arises from brief contamination or localized overheating.
Physico-chemical mechanism of action
A porosity cluster forms when air bubbles or other gases form in the molten pool during welding and cannot escape. This can be due to contamination from dirt or local overheating with too fast cooling.
Metallurgical relevance & risks in welding
A porosity cluster reduces the strength and mechanical properties of the weld. It can lead to cracking or wear problems, especially under load. It can also serve as initiation points for corrosion.
Workshop practice & instructions
To avoid porosity clusters, a clean welding environment is essential. Use a stable heating process and pay attention to the correct cooling rate. For heavily contaminated material, pre-weld cleaning should be done.