Abstract
Laser and hybrid laser-arc welding in thinner materials are now well-established processes in the welding of as well steels as many other materials. Many advantages in comparison with traditional welding processes have been obtained.
Medium gauge structural steels are now also commonly welded by hybrid laser-arc welding and although fibre- and disk-lasers today are being developed to high powers, CO₂-lasers sources are still dominating larger penetration welding. Shipbuilding is the most outstanding industrial example within this area and after more than 15 years of intensive work, laser based welding in structures typical of passenger ships have become generally accepted, and is now integrated in the production at many European shipyards. The paper will summarise this development and the present industrial status will be overviewed.
Penetration depths in excess of approximately 12 mm in structural steel do however continue to be a serious challenge. This is partly due to limitations in the achievable welding depth because the penetration as a function of laser power shows a very non-linear behaviour, and partly to the large molten volume that must be controlled. Recent results in 12-20 mm thickness welded in one pass are presented as are also some multi-pass results in larger thickness.