Fig. 1. Gaussian heat source model

Fig. 2. Characteristics of AlSi10Mg powder. (a) SEM morphology; (b) distribution of particle size

Fig. 3. Computing model and scanning mode. (a) Regional division of the computing domain; (b) hexahedral meshing; (c) dual-scanning paths and monitoring points

Fig. 4. Variation in temperature of monitoring points with time under various scanning spacings. (a) Monitoring point E; (b) monitoring point F

Fig. 5. Distribution of temperature and temperature gradient along the Y-axis (Z=0.180 mm) when the laser scan reaches the monitoring point G under various scanning spacings. (a) Temperature; (b) temperature gradient

Fig. 6. Variation in cooling rate of the molten pool after the second scanning under various scanning spacings

Fig. 7. Flow velocities of molten pool surface under different scanning spacings. (a) Distribution of surface velocity for molten pool under scanning spacing of 50 μm; (b) average flow velocities of zone 1 under different scanning spacings; (c) average flow velocities of zone 2 under different scanning spacings; (d) velocity differences between zones 1 and 2 under different scanning spacings

Fig. 8. Comparisons of average flow velocities for molten pool in track 2 under different scanning spacings. (a) Initial stage (200‒240 μs); (b) transition stage (240‒320 μs); (c) full development stage (320‒400 μs)

Fig. 9. Solidified morphologies under different scanning spacings. (a) Solidified morphology of track 1; solidified morphologies of track 2 under scanning spacings of (b) 50 μm, (c) 70 μm, and (d) 90 μm; (e) variation in solidification surface area of molten channel with time; (f) variation in solidification path height of molten channel along the Y-axis at the cross section of X= 0.2 mm

Fig. 10. Molten pool morphologies under different scanning spacings. (a) Contrast between experimental and simulated results; (b) variation in molten pool width and depth with scanning spacing; (c) variation in the overlap rate of the molten channels with scanning spacing

Fig. 11. Variation in relative density and Vickers hardness with scanning spacing

Fig. 12. Optical microscopy morphologies under different scanning spacings