Fig. 1. X-ray inspection film of connector

Fig. 2. Metal laser melting deposition system

Fig. 3. Schematic of slot size and picture of substrate. (a) Slot size; (b) picture of substrate

Fig. 4. Macro appearance and X-ray inspection pictures of samples formed at different laser powers. (a) 1000 W; (b) 1500 W;

Fig. 5. Distribution width of dense porosity at different laser powers

Fig. 6. Metallographic diagrams of connection area at different laser powers. (a) 1000 W; (b) 1500 W; (c) 2000 W; (d) 2500 W; (e) 3000 W; (f) 3500 W; (g) 4000 W

Fig. 7. Microhardness at different laser powers. (a) Microhardness of fusion line; (b) microhardness outside fusion line

Fig. 8. Schematic of watermark formation

Fig. 9. Scanning electron microscopy (SEM) image of dense porosity

Fig. 10. Flow diagram of porosity after preheating base

Fig. 11. X-ray photographs and metallographic diagrams of preheated sample. (a) Preheating temperature of 50 ℃; (b) preheating temperature of 100 ℃; (c) preheating temperature of 150 ℃; (d) preheating temperature of 200 ℃; (e) preheating temperature of 50 ℃, metallographic diagram; (f) preheating temperature of 100 ℃, metallographic diagram

Fig. 12. Microhardness change of sample before and after preheating

Fig. 13. Tensile stress-strain curves

Fig. 14. SEM images of tensile sample fractures. (a) Sample before preheating; (b) sample after preheating