Influence of the composition of separately laser-generated metal vapor on arc stability.

The presence of metal vapor influences arc stability in both arc and hybrid welding. It is assumed that the composition of the metal vapor, and therefore the substrate material composition, plays an important role due to the different ionization energies of the material elements. In this study, a special setup is used to investigate the influence of metal vapor on the behavior of a vertically oriented arc generated between two equal electrodes by a separate laser-induced vapor generation using a transversally oriented laser beam welding process with additional support materials beside the process zone of the arc. Several aluminum alloys, steel materials, and titanium alloys are used as vapor-producing support materials. The experiments show that the arc voltage increased under the presence of metal vapor, which implies a decrease in arc stability, leading partially to an extinction of the arc. The influence of the ionization energy is evaluated by calculating the average ionization energy for each material composition. In the case of inducing metal vapor into the arc zone, a smaller ionization energy and a lower amount of alloying elements of the support material result in a lower arc voltage increase and, therefore, higher arc stability. A higher effect on the arc stability when using elements with a smaller ionization energy for the second electron than the first argon electron is not measurable. [ABSTRACT FROM AUTHOR]