Laser surface modification of additively manufactured metals: mechanisms, thermal–microstructural evolution, and property enhancement

Additively manufactured metallic components frequently suffer from surface-related limitations, including high roughness, partially fused particles, localized porosity, and tensile residual stresses. These features act as stress concentrators and significantly reduce fatigue life, wear resistance, corrosion performance, and long-term structural reliability. Laser-based surface modification has emerged as a precise and highly controllable post-processing approach capable of improving surface integrity while preserving dimensional accuracy and complex geometries. This review provides a comprehensive synthesis of four major laser techniques laser polishing, laser remelting, laser shock peening, and laser surface texturing and examines the thermal, mechanical, and microstructural mechanisms that govern their effectiveness. Particular attention is given to the influence of process parameters on melt-pool stability, solidification behaviour, grain morphology, and residual stress evolution, and how these factors translate into improvements in hardness, fatigue performance, corrosion resistance, and functional surface characteristics. Alloy-specific responses for stainless steels, titanium alloys, and nickel-based systems are critically discussed alongside practical processing considerations and known limitations. A central contribution of this work is the development of a unified thermal–microstructural framework that systematically links laser input conditions to microstructural transitions and resulting property enhancements. Emerging hybrid laser strategies and data-driven optimization approaches are further highlighted as enabling pathways toward intelligent, scalable, and qualification-ready surface engineering solutions for next-generation metal additive manufacturing.