The effect of altering heat input & torch motion on the grain formation of SS316L material in WAAM

Wire arc additive manufacturing (WAAM) is an effective technique for producing medium to large-size components, due to its convenience and sustainability in fabricating large-scale parts with high deposition rates, employing low-cost and simple equipment, and attaining high material efficiency. Thus, WAAM attracts different industrial sectors and has experienced great growth, particularly over the last decade to overcome production market’s challenges. Consequently, fabricating parts in WAAM, mostly resulted in heterogeneity in microstructure of three different zones towards the buildup direction due to different cooling rates; upper zone (thin surface layer of fine grains), middle zone (undesired large columnar grains covers 90% of the produced part), and lower zone (intermediate columnar grains close to substrate material). Accordingly, producing parts consisting of different zones affect the final component mechanical properties. Therefore, controlling the formation of these zones is a key role in improving WAAM technique. Altering torch motion and cooling rates were found to be effective methods to control the homogeneity of the final component in WAAM.