Combined pore-slag defect
A combined pore-slag defect consists of connected gas inclusions and solid slag particles located in the weld. This leads to uneven stress distribution and increases the risk of cracking.
Physical-Chemical Mechanism of Action
Gas inclusions form due to the absorption of oxygen, hydrogen, or other gases during the welding process. Slag particles can originate from the weld pool or the material surface and remain in the weld. When these elements are spatially connected, a combined pore-slag defect forms.
Metallurgical Relevance & Risks in Welding
This defect leads to uneven stress distribution in the weld, increasing the likelihood of cracking. The hardness and mechanical properties of the material can be impaired because the slag particles and gas inclusions disrupt the structure. This can cause problems particularly under high loads or in critical applications.
Workshop Practice & Instructions
To avoid combined pore-slag defects, it is important to use a clean weld zone and a strong deoxidizer. The melting time should be long enough to allow gas inclusions to escape, but not so long that slag particles enlarge or collect in the weld. Proper cooling is also crucial to ensure a uniform structure and minimal stress.