The corrosion and degradation behaviour of wire arc additively manufactured 316 SS and aluminium bronze alloys

Abstract: Metal additive manufacturing is proving to be a rapidly emerging technology that promises to make considerable disruption to manufacturing practices worldwide. The ability to 3D print metals allows for fast-prototyping, complex designs and direct at-location manufacturing of parts using minimal materials, waste and cost. Wire arc additive manufacturing (WAM) is the leading contender for commercial large-scale 3D metal part production due to its high deposition rate. However, corrosion and degradation behaviour of 3D printed metals are yet to be well-explored and is expected to be different from conventional manufacturing, due to the anisotropy imposed by the layer-by-layer additive process of fabrication. In collaboration with AML3D: a world-leader in large-scale 3D metal WAM, stainless steel and aluminium alloys were investigated due to their desirable weight-to-strength and corrosion resistant qualities. A review of current literature on WAM printing parameters and their influence on microstructure, corrosion behaviour and part degradation reveals little in the area. We report our efforts on 316 stainless steel and aluminium bronze alloys that have been WAM printed, varying the deposition rate, material heating and wire feed velocity. Studies of the corrosion behaviour and microstructure have been investigated using accelerated potentiodynamic corrosion testing and electrochemical impedance spectroscopy (EIS) in 3.5 wt.% NaCl solution, followed by surface characterisation by scanning electron and auger electron spectromicroscopy (SEM and AES/SAM).