Weld strength behavior of laser butt welds

In terms of the process sequence, laser butt welding corresponds to contactless heated tool welding. The difference lies in the heating phase in which the joining zones of the semi-finished products are periodically scanned by an Nd:YAG-laser beam at a high speed (Fig. 1). Tests carried out with laser butt welds with a meltpool, in which the joining zone is plasticised more deeply in the middle than in the outer areas, have shown parameter-independent high weld strengths over a wide range of heating time and joining displacement. Welds without a meltpool, however, showed short-time welding factors of I. The reason for this strength behavior in contrast to heated tool and radiant heater welding must be seen in the temperature distribution in the joining zone. Different cooling processes as well as the state of internal stresses may provide an explanation for this.