Post-processing technologies for additively manufactured metals: surface engineering approaches for superior service performance

AM provides the ability to produce complex metallic parts additively; its performance in demanding tasks is limited due to surface roughness, partially fused particles, and microstructural heterogeneity, inherent in the process. Such inadequacies have negative impacts on fatigue life, corrosion resistance, and dimensional accuracy especially complex geometries. This review categorises the post-processing strategies systematically by type: mechanical, chemical, electrochemical polishing (ECP), and hybrid, with a focus on their performance in terms of surface refinement and defect reduction. An integrated process-microstructure-property model is developed to explain the role of post-processing in controlling phase transformation (α′ → α + β in Ti6Al4 V), grain refinement, dislocation density and evolution of residual stress. Newer techniques such as laser-assisted polishing, ultrasonic nanocrystal surface modification and microwave-assisted methods are critically examined. The review mentions quantitative correlations between functional performance and process parameters, which present a unified avenue for optimising AM components. The work provides a coherent view that connects surface engineering and microstructural control to high-performance applications.