Laser Weldbability of different Al-Zn alloys and its improvement

Abstract

Weld defects - such as porosity and hot cracking - occur especially during the laser beam welding of high-alloyed Al-Zn alloys. This significantly limits the application range of these promising high-strength alloys. In the present study the laser weldability of Al-Zn alloys was investigated regarding welding parameters and chemical composition of the alloys. In addition, the novel approach of the Helmholtz-Zentrum Geesthacht for overcoming the weldability problems was applied to the different Al-Zn alloys in order to assess its capability. It was shown that the laser weldability of Al-Zn alloys deteriorates with an increasing amount of Zn, Mg and Cu. The variation of laser welding parameters did not lead to any improvement of weldability. Only the use of a V foil as additional filler material resulted in promising welding results even for high-alloyed Al-Zn alloys.