Influence of Surface Roughness on Selected Geometric Characteristics of Laser Beam Welded Joints of AW 2099 Alloy

Al-Li alloys are used in various industries owing to their good mechanical and physical properties. However, one of the limiting factors of welding the aluminium alloys by laser beam is the high reflectivity of the beam and thus the reduced efficiency of the laser. Reduction of reflectivity can be achieved by increasing the surface roughness, which may have a beneficial effect on the absorption of the laser, resulting into affecting the weld bead dimensions. The paper deals with the analysis of the influence of surface roughness of welded materials on geometry of welded joints. Specimens of AW 2099 alloy 2099 with a thickness of 3 mm were milled to achieve different levels of roughness, and then laser welded. Characteristic dimensions of the welds (weld surface/root width) were measured. The obtained data were statistically analysed using the ANOVA method, in order to assess statistical significance of the influence of individual roughness parameters on the geometric characteristics of welds. The results of the analysis showed that, within the monitored range and surface roughness parameters, only the influence of roughness parameter Rq, Rz on the weld root width can be considered statistically significant.