Experimental study on morphology, microstructure and mechanical properties of adjustable-ring-mode (ARM) laser welded Al-Mg alloy

Adjustable-ring-mode (ARM) laser welding displays great potential for improving the stability of the molten pool and the weld quality of aluminum alloys through the coaxial attachment of a large-sized ring-beam spot. In this paper, the author embarked on a systematic study on the impact of varied core powers, ring powers, and core/ring power ratios on the weld morphology, microstructure, and mechanical properties of Al-Mg alloy during the laser welding process with ARM. The results showed that the core power led to higher depth of penetration, and the superheating of the molten pool it created caused grain coarsening and reduced properties. The ring beam effectively decreased weld spatter and enhanced the surface roughness of the weld. Furthermore, the ring beam was more likely to obtain a wider columnar crystal zone and a more homogeneous grain size distribution. The welded joints possessed higher tensile strength values when ring beam power was increased from 1.5 to 2 kW due to the improvement of surface flatness and porosity defects by the ring beam.