During the welding process, the surface slag inclusions that can be seen from the outside mainly appear between layers.
A. During multi-layer multi-pass welding, the interlayer coating is not clean; or the surface of the previous layer of weld is not smooth or the surface of the weldment does not meet the requirements.
B. Improper welding operation techniques such as low welding input energy and too fast welding speed.
A. Choose a reasonable welding current and welding speed. The interlayer coating must be cleaned during multi-layer multi-pass welding.
B. Grinding to remove the weld seam with slag inclusion on the surface, repair welding if necessary.