Christoph Turner

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.

Welding of thick plate copper with laser beam welding under vacuum

Today, copper is one of the most important materials and will become even more important in the future. It is used in a wide range of products, industry sectors, and plate thicknesses. The beam welding technologies laser beam welding and electron beam welding achieve high intensities and are thereby suitable to overcome the difficulties in the welding of copper, which are caused by properties such as high thermal conductivity. There is a high demand for the application of the laser beam in the welding of copper, but in industrial applications, a sufficient process capability is currently only achieved with a high welding speed and a high laser power level. At low welding speeds, process instabilities such as weld metal ejections occur. These ejections can cause critical welding defects which have to be prevented. At high welding speeds, the penetration depth decreases dramatically even if a high laser power is applied. In addition, the process control is hampered and the investment costs increase. By laser beam welding in vacuum, the process capability can be increased significantly. Weld metal ejections at low welding speeds are prevented. This increase in process stability can be transferred in a high penetration depth at a comparatively low laser power level. Sound welding of copper at a power level between 4 and 8 kW (intensity level 50–80 kW/mm2) of a multimode solid state laser becomes possible without weld metal ejections. A penetration depth of 3–8 mm is achieved.Today, copper is one of the most important materials and will become even more important in the future. It is used in a wide range of products, industry sectors, and plate thicknesses. The beam welding technologies laser beam welding and electron beam welding achieve high intensities and are thereby suitable to overcome the difficulties in the welding of copper, which are caused by properties such as high thermal conductivity. There is a high demand for the application of the laser beam in the welding of copper, but in industrial applications, a sufficient process capability is currently only achieved with a high welding speed and a high laser power level. At low welding speeds, process instabilities such as weld metal ejections occur. These ejections can cause critical welding defects which have to be prevented. At high welding speeds, the penetration depth decreases dramatically even if a high laser power is applied. In addition, the process control is hampered and the investment costs increase. By lase...

Hybrid laser welding in shipbuilding – Extension of the application range to vertical down welding

The Hybrid Laser Welding (HLW) has become one of the most important manufacturing technologies for an automated and efficient shipbuilding. The technology is successfully used since the early 2000s and mainly applied in the panel manufacturing (flat position groove weld 1G and fillet weld 2F). The target of the research work is to extend the range of application of the Hybrid Laser Welding in shipbuilding to the vertical welding positions 3G (groove weld) and 3F (fillet weld). The welds for wall structures are currently performed by manual vertical-up welding. The implementation of a fully mechanized vertical-down welding system, based on Laser Beam Welding (LBW) and Gas Metal Arc Welding (GMAW) processes will increase the productivity in a huge amount.The Hybrid Laser Welding (HLW) has become one of the most important manufacturing technologies for an automated and efficient shipbuilding. The technology is successfully used since the early 2000s and mainly applied in the panel manufacturing (flat position groove weld 1G and fillet weld 2F). The target of the research work is to extend the range of application of the Hybrid Laser Welding in shipbuilding to the vertical welding positions 3G (groove weld) and 3F (fillet weld). The welds for wall structures are currently performed by manual vertical-up welding. The implementation of a fully mechanized vertical-down welding system, based on Laser Beam Welding (LBW) and Gas Metal Arc Welding (GMAW) processes will increase the productivity in a huge amount.

Vertical-down hybrid welding in ship building - The next innovation step

The ever increasing competitive pressure caused by the worldwide development of ship building capacities requires the application of innovative and highly efficient production technologies in German shipyards. Due to the increase of welding speed and to the increased degree of mechanization, fully mechanised, sensor-supported vertical-down welding (FaSek) entails considerable economic advantages in the joining of vertical welds compared with the currently applied manual vertical-up welding. This is achieved by using the laser-beam GMA hybrid welding method with additional, oppositely arranged GMA torch.The ever increasing competitive pressure caused by the worldwide development of ship building capacities requires the application of innovative and highly efficient production technologies in German shipyards. Due to the increase of welding speed and to the increased degree of mechanization, fully mechanised, sensor-supported vertical-down welding (FaSek) entails considerable economic advantages in the joining of vertical welds compared with the currently applied manual vertical-up welding. This is achieved by using the laser-beam GMA hybrid welding method with additional, oppositely arranged GMA torch.