Porosity reduction in the laser beam welding of aluminium die cast alloys through the overlapping of mechanically induced sound waves

• Published in: Journal of physics. Conference series Vol. 1109; no. 1; pp. 12019 - 12025
• Main Authors: Völkers, S., Böhm, S., Somonov, V.
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.11.2018
• Subjects: Aluminum base alloys; Casting alloys; Cooling rate; Dies; Joining; Laser beam heating; Laser beam welding; Laser cooling; Lasers; Outgassing; Porosity; Release agents; Residues; Sound waves; Weight reduction
• DOI: 10.1088/1742-6596/1109/1/012019
• ISSN: 1742-6588

In recent years, to meet society's increasing demands to reduce environmental pollution, the industry's attention has been drawn to the subject of lightweight construction. Especially die-cast aluminium alloys offer their user a variety of design options for targeted weight reduction. However, a problem with the use of this material is the cohesive connection using welding technology. The main problem are the release agent residues as well as gas and oxide residues, trapped in the die-cast, which diffuse during the welding process in the direction of the liquid aluminium melt and result in a weld porosity. Due to the high heating and cooling rates resulting from the laser beam welding and the resulting outgassing possibilities of the liquid melt, the process of laser beam welding is particularly susceptible to the joining of aluminium die-cast components and, despite its many advantages, can currently only be used by complex and expensive additional measures. This is where the research activities of the Department for Cutting and Joining Manufacturing Processes (tff) start. The department deals with a specific influence on the prevailing melt flow through a sound wave superposition during the welding process. For the coupling of the sound waves, flexibly positionable piezoshakers are used, which allow greater degrees of freedom with respect to the welding geometry.