Laserstrahlschweißen von Metallen mit niedrigsiedenden Legierungselementen

Description

Metals with low-boiling alloying elements are used in many industrial sectors. These elements have a strong influence on evaporation behavior, which leads to an unknown loss of low-boiling alloying elements in the weld seam during laser beam welding. In addition, capillary instabilities occur with these alloys.In order to identify possible solutions, the two topics of selective evaporation and capillary instabilities are being investigated. The investigations are mainly carried out with magnesium- and zinc-alloyed aluminum alloys, as these materials exhibit significantly reduced evaporation temperatures even for low alloy contents.

By comparing mass transfer models with experimental results and adjusting material parameters, the models can be used to predict the alloying element loss and the evaporation flow of low-boiling elements.

As the main result of the investigations, bubble boiling can be identified as the cause of capillary instabilities. The phenomenon is comprehensively characterized, and a formation mechanism is proposed which takes up the findings from the investigations on selective evaporation. In addition, a criterion for bubble boiling is derived.