Effect of process variables on heat transfer and the product quality during layer deposition of Al4043 alloy by wire arc additive manufacturing

In the present work, heat transfer dynamics between the substrate and the deposited metal is investigated to assess its effect on the evolution of defects and the quality of the product. A series of experiments involving the deposition of Al4043 wire were conducted on Al4043 aluminum alloy substrate at a voltage range of 13-19 V. A one-dimensional inverse computational model was adopted to estimate the heat flux transients. The metal/substrate interfacial heat flux was correlated with the microstructure evolution during the solidification of the metal. The experimental results clearly indicated that heat transfer plays a dominant role in the final finish and quality of the product and is controlled by variables, such as voltage, gas flow rate (GFR), wire feed rate (WFR), and forward traversal speed. At an integral heat flow (HF) in the range of 3000-5000 kJ/m2 corresponding to voltages between 13.8 and 14.5 V, argon GFR of 12-15 L/min, and a WFR of 4.1 mm/min, the porosity in the additively manufactured component was found to be minimum. The ultimate tensile strength was found to be 65 and 76 MPa, corresponding to the voltage of 13.5 and 14.5 V, respectively, and decreased to 25 MPa for a higher voltage of 19 V. At the GFR range of 8-10 L/min, the HF was in the range of 450-510 kJ/m2 with increased porosity (33%-42%). Porosity was found to decrease (15%-22%) with 12-15 L/min range of GFR and the corresponding HF was in the range of 700-950 kJ/m2. The specimens fabricated under these optimal parameters exhibited superior mechanical properties.