Effect of Deposition Rate and Deposition Speed During the Fabrication of Iron Aluminides with 10 wt.% of Al Using CMT-TWAAM Process

Iron aluminides are used in fossil fuel energy systems and rotors of turbochargers in the automobile industry due to their excellent oxidation and corrosion properties. Developing iron-iron aluminides is still challenging because of a lot of differences in the various properties of iron and aluminum. In the present work, iron aluminide thin walls are fabricated with a composition of 10 wt.% of Al (AA 4043) and 90 wt.% of Fe (ER 70S-6), using CMT technology by gas metal arc welding-based twin wire arc additive manufacturing process. Electrodes are selected in CMT mode to minimize the overall heat input in the process. Fe wire is selected as lead wire to form a stable melt pool and Al wire as trail wire to transfer the molten metal directly into the melt pool. The deposition process is carried out at 0.66, 1, and 1.28 g/s deposition rates with 5 and 10 mm/s deposition speeds to fabricate five-layered iron aluminide thin-wall structures. The macro-dimensional analysis and microstructural studies reveal the variation in grain morphology from bottom to top. V-I waveforms of electrodes and thermal profiles are recorded and used for heat input and cooling rates of layers calculations. Cooling rates affect the microstructural features and subsequently the various mechanical properties. The results reveal that, as the deposition rate increased at a low deposition speed, the depth of penetration into the substrate during the first layer deposition is high. The deposition rate and the deposition speed influence the dimensions of deposited iron aluminide thin walls. XRD and microhardness results confirm the formation of iron-rich intermetallic phases such as Fe3Al and FeAl in the deposited iron aluminide structures.