Sparse modeling of dominant factors affecting porosity formation in laser powder bed fusion of aluminum alloy

Abstract

The dominant factors affecting porosity formation in laser powder bed fusion (PBF-LB/M) of an aluminum alloy were investigated through sparse modeling with the cross-sectional pore area ratio as the target variable and the process parameters of PBF-LB/M and the melting and solidification conditions of the alloy as the explanatory variables. A combination of a few explanatory variables that did not significantly increase the mean squared error for the relationship between the measured pore area ratios and the ratios estimated via the regression equations was found through lasso regression and backward elimination, which indicated that the energy density (one of the process parameters) and melt-pool depth (one of the melting conditions) were the dominant factors affecting the pore area ratio. The obtained regression coefficients for the energy density and melt-pool depth were negative and positive, respectively. In addition, the relationship between the energy density and melt-pool depth was curvilinear. These results suggest not only that the pore area ratio increases with the energy density and melt-pool depth but also that it decreases with an increase in the energy density or a decrease in the change rate of the pool depth under the range of the slow increase in the pool depth with an increase in the energy density.