Wire arc additive manufacturing (WAAM) is suitable for printing medium-to-large complex parts with structural integrity while reducing material wastage, and lead time, improving the quality and customized design for functional components. Aluminium alloys are one of the most commonly used metallic materials in manufacturing parts for aerospace and automotive applications due to their lightweight, excellent strength, and corrosion resistance properties. Aluminium alloys have been employed in the WAAM process to produce parts for the aerospace and automotive industries. In this paper, various research works associated with the application of WAAM of aluminium alloys for aerospace and automotive industries, their metallurgical characteristics, and mechanical properties have been reviewed and discussed in detail to identify the research gap and future research directions. This paper is patterned to provide a comprehensive review of WAAM of aluminium alloys for the production of parts in the aerospace and automotive industries. Abbreviations: AM: Additive manufacturing; Al: Aluminium; Bi: Bismuth; BIW: Body in white; CNC: Computer numerical machines; CMT: Cold metal transfer; CNN: Convolutional neural networks; CL: Curved layer; DE-GMAAM: Double-electrode gas metal arc additive manufacturing; DWAAM: Double wire arc additive manufacturing; DMD: Direct metal deposition; DMLS: Direct metal laser sintering; DED-arc: Directed energy deposition arc; 3D: Three-dimensional; EAC: Environmentally assisted cracking; EBM: Electron beam melting; FCI: Fatigue crack initiation; Fe: Iron; GTAW: Gas tungsten arc welding; GMAW: Gas metal arc welding; HE: Hydrogen embrittlement; HAZ: Heat-affected zone; HWAAM: Hot wire arc additive manufacturing; IISCC: Irradiation induced stress corrosion cracking; Li: Lithium; Mg: Magnesium; Mn: Manganese; Ni: Nickel; OL: Online cooling; Pb: Lead; PAW: Plasma arc welding; RS: Robotic system; SCC: Stress corrosion cracking; SLM: Selective laser melting; SCG: Short crack growth; SLC: Super light car; Si: Silicon; Ti: Titanium; Zr: Zirconium

Additive manufacturing (AM), also known as 3D printing, is a process for creating prototypes and functional components achieved by consolidation of material layer upon layer. Applications of AM technologies have been witnessed in the healthcare, automotive, architecture, power generation, electronics and aviation industries. Some of the main benefits of AM include effective material utilisation, new design possibilities, improved functionality of the products and flexible production. The opportunities for the applications of additive manufacturing in the oil and gas industries are only just being explored. In this study, a review of the potential opportunities of AM technologies in oil and gas industries was reported. The adoption of the AM technologies necessitated the need for a rethink on design for manufacture and assembly of oil and gas component parts such as high-tech end burners, metal fuel nozzles, and submersible pump components amongst others. The possibility of employing AM technologies on-site for the production of spare parts for replacement of damage components in oil and gas equipment and facilities is commendable, as this brings about reduction in production downtime and replacement cost. The future of AM in the oil and gas industries is highly promising, however before AM can actualize its full-fledged potentials in these industries, further research is required in the area of new materials development and processing, improved surface finish of AM fabricated parts, enhanced fabrication speed and parametric optimisation to improve the mechanical properties of the fabricated components.

Steels are majorly used for diverse structural applications; however, they suffer severe degradation in a corrosive environment which necessitates the need for a protective surface coating. In this paper, the electrochemical study of MgZnCa alloy thin film coating on an AISI 304 stainless steel was reported. The study intends to investigate the influence of coating thickness on the electrochemical performance of the ternary MgZnCa alloy thin film. The polarization results indicated that better corrosion resistance is achieved when the MgZnCa coating is applied on the steel substrate, as the corrosion current density of the 4 µm coating (0.28 mA/cm²) is lower than for the uncoated substrate (0.44 mA/cm²). As the MgZnCa coating thickness increases from 4 to 6 µm, a decrease in the corrosion density with a resultant increase in the corrosion potential was observed. The microstructural characterization revealed fewer corrosion attacks for the coated substrates as compared with the uncoated material with the presence of more degradation products. The corrosion resistance of the steel substrate is enhanced by the application of MgZnCa coating and increasing coating thickness is significantly beneficial.