A state-of-the-art review on metal additive manufacturing: milestones, trends, challenges and perspectives

This paper presents a comprehensive review of metal additive manufacturing (MAM). MAM processes are promising technologies for the upcoming industrial manufacturing system as they offer tremendous capabilities and advantages over traditional manufacturing such as freedom of design, structural optimization, production with almost negligible waste, and fabrication of complex structures. This review paper provides a comprehensive analysis of MAM, analyzing its classification into various techniques such as powder bed fusion, directed energy deposition, sheet lamination, metal binder jetting, and material extrusion. Additionally, the paper investigates the range of materials utilized in MAM, encompassing both conventional metals and alloys, as well as emerging novel materials. Metallurgical aspects, including processing parameters, solidification, metallurgical mechanisms, microstructural evolution, and mechanical properties, are thoroughly explored and discussed. Furthermore, various major challenges faced by the industrial community while adopting these technologies are briefly covered in this paper along with some of the recently reported solutions. Lastly, this paper reviews some of the important future trends and development activities currently underway on the path of progress of these technologies. Overall, this paper provides a piece of important knowledge about MAM, including their classification, materials, metallurgical aspects, challenges, and future trends and development opportunities to help researchers and the industry.