An Experimental Investigation on Microstructure, Mechanical Properties and Corrosion Performance of CMT-Wire Arc Additively Manufactured Al-4043 Alloy

The wire arc additive manufacturing process (WAAM) has drawn incredible potential to manufacture non-ferrous alloys such as Aluminium and Magnesium. The deposition of Aluminium using a conventional WAAM process resulted in various defects such as porosity, cracks and tensile residual stress owing to high heat input. Therefore, to address these challenges, cold metal transfer wire arc additive manufacturing process (CMT-WAAM) is used to deposit 4043 Al alloy. The microstructure, mechanical properties and corrosion performance of Al 4043 are evaluated to ascertain the quality of deposited parts. The XRD peak intensity and microstructure shows that the main phases are α-Al and MgSi2 eutectics distributed along the grain boundaries of the Al matrix. The grain size of the bottom section is relatively smaller than the middle and top sections due to the high thermal gradient at the beginning of the deposition. Therefore, the hardness increases from the bottom to the top section of the thin wall. In addition, variations in the fraction of secondary phases are also responsible for the variation in hardness. The average UTS and % EL of travel direction (TD) are 177 ± 5 MPa and 20 ± 0.3%, which are relatively higher than the average UTS (164 ± 2 MPa) and % EL (17 ± 0.5%) of build direction (BD). However, the differences are only 10 ± 3 MPa and 2 ± 0.3% EL, exhibiting isotropic mechanical properties. The corrosion rates of the bottom, middle and top sections are 0.172, 0.116 and 0.102 mm/year, which are comparable, exhibiting uniform corrosion resistance of the deposited thin wall.