A study on the effect of substrate heating and cooling on bead geometry in wire arc additive manufacturing and its correlation with cooling rate

In the present work, the effect of process parameters, substrate heating and cooling on bead geometry during the wire arc additive manufacturing of Inconel 625 on EN 8 steel is investigated. Further, the molten pool thermal history during the deposition was monitored using an IR pyrometer and the effect of these parameters on cooling rate was investigated and correlated with bead geometry. The cooling rate was found to increase with increase in travel speed from 500 mm/min to 700 mm/min while decreased with increase in energy input by varying the applied current between 190 A and 250 A. Though the bead geometry was found to vary with substrate heating, it was found to saturate with increase in current from 190 A to 250 A. Similarly, with increase in current to 250 A, the cooling was found to be ineffective due to increased amount of heat input. Cooling rates were found to effectively indicate these saturation limits which would help in process monitoring and control.