Comparison of spatter characteristics in fiber and CO₂ laser beam welding of aluminum alloy

Spatters in laser penetration welding of aluminum alloys can pollute the focusing system, which would affect the processing stability and welding quality. Furthermore, the spatter characteristics can reflect the laser welding process in some degree. In this paper, the spatter characteristics in fiber and CO₂ laser welding of 6061-T6 aluminum alloy are investigated, and the reasons for the difference of the spatter characteristics are discussed. Dynamic behavior of spatters is recorded in real-time using a high-speed camera. The spatter particles are captured and measured experimentally. Probability density functions (PDFs) about the spatter velocity and particle size are fitted by Ordinary Least Squares (OLS) method in χ² test. The result indicates that the spatter speed obeys Gaussian distribution and the particle size follows Lognormal distribution in both cases. The statistical speed of spatters is slower and the statistical diameter is greater in CO₂ laser welding. Moreover, under 95% confidence, the particle size’s PDF is more subject to Lognormal distribution with a much smaller residual mean square (RMS) of 3.26×10⁻³ in fiber laser welding than that of 0.109 in CO₂ laser welding.