Fig. 1. Morphology of Ti-6Al-4V powder

Fig. 2. Schematics of (a) edge line of overhanging surface and (b)(c)(d)(e)(f) laser scanning path under different scanning line angles

Fig. 3. Overhanging hole specimen formed by SLM

Fig. 4. Overhanging round hole structure formed by SLM with laser power of 240 W and scanning speed of 1650 mm·s-1. (a) Schematic; (b) internal surface morphology

Fig. 5. Schematic of step effect in overhanging round hole structure

Fig. 6. Roundness of overhanging round hole versus laser power

Fig. 7. Collapse amount on overhanging surface of round hole versus laser power

Fig. 8. SEM images of surface morphologies in part Ⅱ of overhanging holes under different laser powers. (a)(b) 120 W; (c)(d) 150 W; (e)(f) 180 W;(g)(h) 210 W; (i)(j) 240 W

Fig. 9. Overhanging surface roughness of round holes formed by SLM. (a) Ra; (b) Rz

Fig. 10. (a) Laser scanning trajectory in part III of overhanging hole; (b) laser scanning trajectory in part II of overhanging hole; (c) schematic of forming of overhanging round hole side

Fig. 11. Effect of number of contour scans on different areas of inner surface of overhanging round hole formed by SLM

Fig. 12. Surface morphologies of part Ⅱ and part Ⅲ of overhanging round hole formed by SLM. (a) 1; (b) 2; (c) 3