Critical Analysis of Inter-layer Dwell Time on the Properties of Wire Arc Additive Manufactured Steel Structure: Experimental and Modelling Approach

Abstract

Wire arc additive manufacturing (WAAM) causes significant heat accumulation within the deposited layers making it difficult to achieve necessary geometrical accuracy and built properties. A cost-effective technique to mitigate build-up heat and improve the thermal cycle is accomplished with the introduction of an inter-layer dwell time (ILDT). The study investigates the impact of ILDTs of 60, 90, 120, 150, and 180 s on the properties of the printed parts. The grain refinements were achieved at higher ILDT with no appreciable changes in the compositions. However, a slight increase in oxides and \(\delta \)-ferrite was detected. The study found improved part density, mechanical and tribological performance while reduced corrosion-resistant properties with increased ILDT. Furthermore, to understand the effect of ILDTs on location-based thermal cycling and distribution, numerical models of the process were established. The peak temperature gradually reduces with an increase in ILDT. Heat accumulations within the three-layered WAAM-built structure lessen by 70% approximately with increases in ILDT from the 60 s to 180 s. The results observed repeated thermal cycles of the previously deposited layers and reduction of peak temperatures with subsequent layer deposition irrespective of the ILDTs. The trough temperature slightly reduced with ILDT; however, at higher delay periods the variations were found to be more stable. The study discovered too low and too high ILDT is detrimental and therefore an appropriate mid-range ILDT of 120 s is suggested to fabricate medium-size WAAM-built components based on experimental and numerical investigation considering overall production time and functional properties.