Impact of cold metal transfer variants on the mechanical and microstructural properties of aluminum alloys in wire arc additive manufacturing: a critical review

This critical review examines how cold metal transfer-based wire arc additive manufacturing (CMT-WAAM) addresses long-standing issues in aluminum alloy processing within the additive manufacturing (AM) field. CMT-WAAM, which employs the CMT welding process developed by Fronius, is known for its low heat input, a controlled short-circuiting arc, minimal heat input, precise metal transfer, and spatter-free deposition. In this technique, a wide range of metallic materials can be used, including steel, stainless steel, titanium alloys, and aluminum alloys. Among all these materials, aluminum alloys continue to present significant challenges due to their metallurgical and thermal characteristics, often leading to defects such as residual stresses, porosity, and inconsistent microstructures. To improve the mechanical attributes of aluminum alloys produced through the WAAM process, a blend of process optimization, alloy modification, and post-processing techniques has been widely adopted in the literature. In this review work, we examine the role of the CMT variant in further enhancing the properties of WAAM-produced components by managing defects, such as residual stresses and distortions, optimizing the microstructure (including grain size and phase distribution), and improving tensile strength, hardness, ductility, surface quality, and fatigue life of the WAAM-produced parts. This work highlights the importance of the CMT variant in creating defect-free parts, as well as improving the mechanical and microstructural properties of aluminum alloys. Finally, it discusses conclusions and recommendations for future directions in this area.

Recommended citation: Omiyale, B.O., Jack, T.A., Ogedengbe, I.I., Odeyemi, J., Mishra, D., Ogbeyemi, A., & Zhang, W. C. (2025). Impact of cold metal transfer variants on the mechanical and microstructural properties of aluminum alloys in wire arc additive manufacturing: a critical review. *The International Journal of Advanced Manufacturing Technology, 140*, 1183–1210.
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