Correlation of process parameters and porosity in laser welding of 7A52 aluminum alloy using response surface methodology

The article presents an experimental investigation of the effect of process parameters (i.e. laser power, welding speed and defocus distance) on porosity in laser welding of 7A52 aluminum alloy. A three-factor, three-level factorial Box-Behnken design (BBD) of response surface methodology (RSM) was used to complete the design matrix with the objective of optimizing the process parameters. Multiple regression models were established to predict the correlation between the selected process parameters and porosity, and then were tested for adequacy using analysis of variance (ANOVA). The results showed that macro pores in laser welding seam were mainly keyhole induced, and porosity susceptibility was mostly dominated by welding speed. The optimal combination of process parameters is the laser power of 3.5kW, welding speed of 10.0mm/s, and the defocus distance of +4.0mm. Under the optimal process parameters, superior weld seams without macro pore were produced. The predicted porosity area fraction with RSM models was confirmed to be in good agreement with the measured values of validation experiments.