Fig. 1. Schematic of experimental equipment and sample surface morphologies. (a) Schematic of experimental equipment; (b) surface topography of low-roughness sample; (c) surface morphology of flannelette polishing sample

Fig. 2. Cross sections of single-channel laser polished pools under different parameters. (a1)-(a3) Different powers; (b1)-(b3) different scanning speeds

Fig. 3. Three-dimensional morphologies of single-channel laser polished pools under different parameters. (a1)-(a3) Different powers; (b1)-(b3) different scanning speeds

Fig. 4. Three-dimensional morphologies of single-channel polished surfaces under same energy density. (a) Laser power of 250 W and scanning speed of 300 mm/s; (b) laser power of 375 W and scanning speed of 450 mm/s; (c) laser power of 500 W and scanning speed of 600 mm/s; (d) laser power of 625 W and scanning speed of 750 mm/s

Fig. 5. Profiles of single-channel polished surfaces under same energy density. (a) Laser power of 250 W and scanning speed of 300 mm/s; (b) laser power of 375 W and scanning speed of 450 mm/s; (c) laser power of 500 W and scanning speed of 600 mm/s; (d)laser power of 625 W and scanning speed of 750 mm/s

Fig. 6. Cross sections and profiles of single-channel polished pools under same energy density. (a) Cross sections of single-channel polished pools; (b) profiles of single-channel polished pools

Fig. 7. Schematics of continuous laser single-channel polishing mechanism. (a) Heat input; (b) formation of molten pool; (c) surface melting flow; (d) solidification molding

Fig. 8. Three-dimensional morphologies of two-channel lap polished surfaces under different filling line spacings. (a) 0.01 mm;(b) 0.02 mm; (c) 0.04 mm; (d) 0.06 mm; (e) 0.08 mm

Fig. 9. Profiles of two-channel lap polished surfaces under different filling line spacings. (a) 0.01 mm; (b) 0.02 mm; (c) 0.04 mm;(d) 0.06 mm; (e) 0.08 mm

Fig. 10. Mechanism diagrams of continuous laser parabolic spacing affecting surface morphology. (a) Low line spacing; (b) high line spacing

Fig. 11. Surface topography and 3D surface topography after one laser polishing. (a) Surface topography; (b) three-dimensional surface topography

Fig. 12. Surface topography and 3D surface topography after two laser polishings under orthogonal scanning. (a) Surface topography; (b) three-dimensional surface topography

Fig. 13. Schematics of scanning strategy. (a) Final formed region; (b) schematic of scanning path

Fig. 14. Surface topography and 3D surface topography after four laser polishings under orthogonal scanning + unlapped area backfill scanning. (a) Surface topography; (b) three-dimensional surface topography

Fig. 15. Surface roughnesses under different scanning strategies

Fig. 16. Cross section and hardness after laser polishing. (a) Metallographic structure diagram of cross section; (b) hardness distribution

Fig. 17. Schematic of EDS line scanning of laser polished section

Fig. 18. Element distribution of Laser polished section

Table 1. Single channel polishing parameters

Table 2. Parameter table of single-channel laser polishing under same energy density

Table 3. Experimental parameters of two-channel lap polishing