Fig. 1. OM morphology of cladding layer^[1,3]. (a) Molten pool with fish scale shape; (b) columnar grains in molten pool and cellular subgrain structure in the grains; (c) morphology of transition layer; (d) morphology of interface between the transition layer and strengthening layer

Fig. 2. OM morphology of Al-Cu-Mg parts produced by SLM^[5]. (a) Morphology of the laser tracks corresponding to alternating x/y-raster filling strategy; (b) detail of the scanning tracks in Fig. (a)

Fig. 3. EBSD spectrum and corresponding 〈100〉 pole figure of cladding layer of AlSi10Mg parts^[6]. (a) EBSD spectrum; (b) 〈100〉 pole figure

Fig. 4. Microstructure morphology of Ti-6Al-2Zr-2Sn-3Mo-1.5Cr-2Nb parts produced by two sets of process parameters^[7]. (a) Laser power P = 2500 W, scanning speed V_b = 50 mm/s, and spot diameter D = 3 mm; (b) P = 1800 W, V_b = 10 mm/s, D = 3 mm

Fig. 5. Schematic of the microstructure distribution of Inconel 718 alloy fabricated by SLM^[9]

Fig. 6. Microstructure of 300M steel parts at different positions^[13]. (a) Bottom of 300M steel parts; (b) middle of 300M steel parts; (c) top of 300M steel members

Fig. 7. SEM images of the Al-Zn-Mg-Cu parts^[14]. (a)(b) Parts produced by SLM (white phase is η phase); (c)(d) ST6 parts

Fig. 8. SEM images of cladding layer^[15]. (a) Top of cladding layer; (b) precipitates

Fig. 9. Morphology of surface and cross section microstructure of LMD low alloy steel^[21]. (a)?(c) Morphology of surface microstructure; (d)?(f) morphology of microstructure of cross section

Fig. 10. Direction representation of the temperature gradient in the different shape molten pool^[30]. (a) Molten pool with smaller weld width and larger weld depth; (b) molten pool with larger weld width and smaller weld depth

Fig. 11. Microstructure morphology of cladding layer produced at different mass deposition rates^[51]. (a) 6 g/min; (b) 11 g/min; (c) 15 g/min; (d) 25 g/min