Surface tension generated defects in full penetration laser keyhole welding

During laser keyhole welding of thin plates, the melt pool is relatively wide compared to the plate thickness. Under certain conditions, an elongated keyhole can be created and a permanent hole is sometimes left in the weld seam. The generation of such holes is determined by surface tension effects in the melt which can generate a self-sustaining geometry at the rear of the melt pool. The geometry of the shape is known as a catenoid and has clear geometrical limits.