Porous metal transpiration cooling structures fabricated via laser powder bed fusion with continuous and intermittent scanning strategies

● Novel LPBF intermittent scanning for porous metal transpiration cooling structures. ● Intermittent scanning design: cyclic "long scan line–gap–short scan line–gap". ● Superior pore connectivity/permeability of Intermittent scanning vs. continuous scanning. ● Both strategies exhibit effective transpiration cooling at 1 MW/m² heat flux. ● Intermittent for low heat flux/limited pressure, continuous for strict temperature control. Transpiration cooling is a critical, efficient, and active thermal protection technology for components in extreme environments. Porous metals are the cornerstone of such structures, with their core mechanism relying on cooling media phase change for latent heat removal, imposing stringent requirements for precise pore structure regulation and controllable fabrication. Laser powder bed fusion (LPBF) is ideal for this purpose because it enables tailored pore modulation. This study fabricated a porous In718 alloy via a conventional continuous scanning strategy and a novel intermittent scanning strategy (cyclic “long scan line–gap–short scan line–gap”). The pore structure and thermal protection performance were characterized by 2D morphological analysis, micro-computed tomography, and flame ablation tests. Compared with the continuous strategy, the intermittent design achieved larger average pore/throat radii, higher coordination numbers, and elevated porosity, realizing the synergistic optimization of pore parameters to significantly enhance 3D spatial connectivity and permeability. Under a 1 MW/m² heat flux, both strategies met thermal protection demands but exhibited distinct advantages: the continuous scanning strategy enables superior temperature control via a stable surface liquid film, while the intermittent strategy operates at a lower water supply pressure and maintains structural integrity post-ablation. These findings indicate that the novel intermittent strategy is suitable for low-heat flux/limited-pressure scenarios, while the continuous strategy is reliable for stringent temperature control requirements.