Effect of shielding gas flow rate on cladding quality of direct laser fabrication AISI 316L stainless steel

Abstract Direct laser fabrication (DLF) has been widely used as an additive manufacturing technology. However, the effect of shielding gas flow rate and interaction among other parameters such as laser power, scanning speed, and powder feed rate in fabrication have not been studied. In this study, four factors were evaluated by two levels of full factorial experiment and response surface methodology (RSM). Thus, the interactions between processing parameters affecting two responses (shape factor and dilution rate) were determined, and regression models for two responses related to shielding gas flow rate were statistically evaluated for the first time. Interactive optimization was performed using contour and surface plots. Hence, the optimum combinations of four parameters were verified by metallurgical and mechanical analyses. More uniform surface profiles and finer microstructures can be obtained by adjusting the shielding gas flow rate. The results show that shielding gas flow rate and its interaction with other parameters for two responses play an important role in fabricating parts of AISI 316 L stainless steel. This fundamental study provides the significance of this parameter and better understanding of interaction between multiple processing parameters.