Corrosion behaviour Study of WAAM deposited magnesium alloy

In recent years AZ31B magnesium alloy is gaining popularity as biomedical implants. Along with the biocompatibility, comparable tensile behaviour to the human bone, self desolving nature in human fluid and osteo promotive nature of AZ31B alloy for human tissue growth make it excellent candidate for temporary implants. Wire arc additive manufacturing (WAAM) is utilized here to deposit the AZ31B alloy. Thin wall (single line) structure has been deposited. The printed specimen has been evaluated for macrostructure analysis, Microstructure analysis, density measurement, Hardness, Tensile testing and corrosion study. There were no voids observed during macrostudy in the deposition. However, the density of the deposition was found 1.728±0.002 g/cc, which is slightly lower than the rolled base plate (1.77 g/cc). The microstructures of the deposited WAAM components contained mainly equiaxed grains (α-Mg solid solution) with a mean size of around 25±9 microns and plentiful intergranular precipitates (Mg17Al12 phase). Grains were found coarser in the middle layers and finer in the bottom and top layers. Almost uniform hardness of 58.43 ± 10 HV was observed from bottom to top of the deposition. The percentage elongation (%ε) and ultimate tensile strength (UTS) for WAAM deposition were found to be 19.64 ± 2 and 216.99 ± 5 MPa, respectively. Corrosion study reflects that the deposited sample has comparable corrosion resistance and is even relatively slower corrosion rate (1.08 mm/year) compare to base plate (2.41 mm/year) in 3.5% NaCl solution during potentiodynamic polarization test (PDP).