Laser-multi-pass narrow-gap welding - An innovative joining technology

Laser beam welding has established itself due to the achievable high process speeds and the extremely concentrated and thus reduced heat input into the joining partners in many industrial areas. However, it has not yet been used in the production of thickwalled components due to the technical process limits with regard to the maximum welding depth to be achieved. In order to overcome the economic (I.), technological (II.) and property-related (III.) disadvantages of conventional welding technologies, e.g: I. low welding speed, large quantities of expensive filler material, II. large heat input per unit length, large welding distortion and III. large heat input, large heat effected zone (HAZ) width with damaged microstructure and reduced high temperature properties, laser beam welding should be made available as a potential welding technology for industry tp produce large components e.g. for modern power plants. The process development of a multilayer laser beam welding process, the Laser-Multi-Pass Narrow-Gap (Laser-MPNG) welding, was the subject of this work. The experimental work was carried out using the nickel superalloy Alloy 617 occm which was a promising candidate work for future high-temperature and high-pressure applications. The aim is to develop a welding technology suitable and to characterize the mechanical properties of the welded joints both at room and application temperature (700°C).