Laser beam welding under vacuum of high grade materials

Currently, three welding processes are used in the manufacturing of large scale work pieces with high weld seam depths. The gas metal arc welding and the submerged arc welding processes are characterized by a comparatively low penetration depth and welding speed, the use of welding consumables and a high energy input per length. Electron beam welding is suitable for single pass welding of high wall thicknesses, but a fine vacuum is needed, x-ray radiation is generated, the process is prone to magnetic fields, and the technology has to face a low market penetration. Laser beam welding under vacuum (LaVa) is on its way to become a new and superb option for these welding tasks. The paper at hand presents the latest results of a research project which targets the qualification of LaVa for the welding of heavy-walled steel structures made of unalloyed steel or duplex stainless steel. The achieved results demonstrate that, in comparison to laser beam welding at atmospheric pressure, an increase of the penetration depth and a high process stability can be achieved, whereby economic advantages and a high weld seam quality are realized. On the other hand, the latest results of the application of LaVa for the welding of nickel-base alloys, copper, and titanium are presented. It is shown that LaVa is suitable for the welding of these materials. A high process stability is achieved; spattering is minimized; and high penetration depths are achieved.