Parametric Study of Fiber-Laser Circular Microtextures on AA2024-T3: Influence of Scale Factor and Scan Speed on Wettability and Roughness

<p dir="ltr" style="line-height:1.295;margin-top:0pt;margin-bottom:8pt;"><span style="font-size:12pt;font-family:'Times New Roman',serif;color:#000000;background-color:transparent;font-weight:700;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre;white-space:pre-wrap;">Abstract</span> <span id="docs-internal-guid-4e5e015e-7fff-fe17-bb2b-63772d41e5a1"></span> <p dir="ltr" style="line-height:1.3800000000000001;text-align: justify;margin-top:0pt;margin-bottom:8pt;"><span style="font-size:12pt;font-family:'Times New Roman',serif;color:#000000;background-color:transparent;font-weight:400;font-style:normal;font-variant:normal;text-decoration:none;vertical-align:baseline;white-space:pre;white-space:pre-wrap;">AA2024-T3 plates were circularly microtextured using a 1064-nm pulsed fiber laser (100 W, 100 kHz) to examine how scale factor (SF = 100, 150, 250 µm) and scan speed (250, 500, 750 mm s⁻¹) tune wettability and roughness. Sessile-drop tests with 5 ± 0.5 µL DI water and ISO 25178 profilometry (Nanovea PS-50, 3×3 mm, 5 µm step) quantified responses. Contact angle spanned 69–96° relative to the 92° untextured reference. For fixed speed, SF showed a non-monotonic trend: at 250 mm s⁻¹, θ decreased from 96° (SF100) to 77° (SF150), then increased to 87° (SF250); the same pattern occurred at 500 mm s⁻¹ (87 to 70 to 77°) and 750 mm s⁻¹ (85 to 69 to 86°). The most hydrophilic state was 69° at SF150/750 mm s⁻¹ (−23° vs reference). Areal roughness Sa ranged from 0.711 µm (SF250/750 mm s⁻¹) to 3.267 µm (SF100/750 mm s⁻¹). Optical microscopy revealed parameter-dependent rim continuity, spatter, and HAZ width; SF150/750 mm s⁻¹ produced the most homogeneous rings, whereas SF250/750 mm s⁻¹ generated shallow, partially discontinuous rims. Correlating Sa and θ indicates that topology plus rim integrity, rather than roughness amplitude alone, governs wetting-enabling targeted tuning of AA2024-T3 surfaces for fluid-contact applications.</span>