2026 Straub LPBF Porosity Control Review

Porous metal structures provide unique capabilities for energy absorption, thermal management, and fluid transport, particularly for aerospace platforms. This review examines parameter-based geometrically-undefined porosity fabrication in laser powder bed fusion, a process that allows for unprecedented spatial control of porosity compared to conventional techniques. We identified two approaches for fabricating porous metals via powder bed fusion: geometrically-defined porosity and geometrically-undefined porosity. Despite the extensive research on geometrically-defined structures, the latter, which leverages strategic adjustments in processing parameters, remains underexplored. This review synthesizes experimental findings across various alloy systems, discussing how parameters such as laser power, scan speed, hatch spacing, and layer thickness influence pore density, distribution, and morphology. Notably, we highlight advantages of geometrically-undefined porosity, including the potential for finer feature sizes, gradient porosity transitions, and reduced manufacturing complexity. We also address the influence of porosity on mechanical, thermal, electrical, and permeability properties, while identifying research gaps and potential applications for this emerging technique, thereby providing a comprehensive overview of the state-of-the-art in this field.