What can cause "slag inclusions" in a weld?

Slag inclusions in a weld primarily occur due to the failure to properly remove slag from previous layers or through improper welding technique. During the welding process, slag forms on the surface of the weld pool as a result of flux material used to stabilize the arc and protect the weld from contaminants. If this slag is not adequately removed before adding subsequent layers of weld material, it can become trapped within the weld as it solidifies, leading to inclusions.

Additionally, if improper welding technique is employed—such as inconsistent travel speed, incorrect angle of the electrode, or not allowing the weld pool to properly form and cool—it can also contribute to the entrapment of slag. Both scenarios hinder the integrity of the weld, resulting in defects that can compromise strength and overall quality.

The other options can contribute to different welding issues but do not directly lead to slag inclusions resulting from the specific scenario of slag being trapped from previous layers or technique flaws.