Fig. 1. Machined repair tank. (a) Numerical control carving machine tool; (b) repair groove shape; (c) repair groove size

Fig. 2. Schematics of laser experimental platforms. (a) Schematic of conventional laser device; (b) schematic of figure-8 swing laser device; (c) schematic of swing trajectory

Fig. 3. Schematic showing microhardness and friction and wear tests. (a) Schematic showing surface microhardness test; (b) schematic showing cross-section microhardness test; (c) schematic showing friction and wear test

Fig. 4. Cladding model

Fig. 5. Thermophysical properties of Fe-based alloy powder and Cr12MoV steel. (a) Density; (b) specific heat; (c) thermal conductivity; (d) Young’s modulus

Fig. 6. Temperature distributions in the repair layer. (a) Surface temperature at conventional laser mode; (b) surface temperature at figure-8 swing laser mode; (c) cross-section temperature at conventional laser mode; (d) cross-section temperature at figure-8 swing laser mode; (e) node temperature at conventional laser mode; (f) node temperature at figure-8 swing laser mode

Fig. 7. Surface and cross-sectional morphology of repair layer at different laser modes. (a) Macroscopic surface morphology of repair layer at conventional laser mode; (b) macroscopic surface morphology of repair layer at figure-8 swing laser mode; (c) flaw detection of repair layer at conventional laser mode; (d) law detection of repair layer at figure-8 swing laser mode; (e) cross-sectional morphology of repair layer at conventional laser mode; (f) cross-sectional morphology of repair layer at figure-8 laser swing mode

Fig. 8. Microstructures of the cross-section of the repair layer at different positions of the same depth at different laser modes. (a) Microstructure observation positions; (a1)(b1)(c1) microstructures of the repair layer at different positions at conventional laser mode; (a2)(b2)(c2) microstructures of the repair layer at different positions at figure-8 swing laser mode; (b) area fraction of dendrite in the repaired layer at different laser modes; (c) average grain size of repair layer at different laser modes

Fig. 9. Microstructures of the longitudinal section of the repair layer at different positions of the same depth at different laser modes. (a) Microstructure observation positions; (a1)(b1)(c1) microstructures of the repair layer at different positions at conventional laser mode; (a2)(b2)(c2) microstructures of the repair layer at different positions at figure-8 swing laser mode

Fig. 10. Microstructures of repair layer surface and interface bonding zone at different laser modes. (a) Surface microstructure observation positions; (b) interface bonding zone observation positions; (a1)(b1) microstructures of repair layer at different surface positions at conventional laser mode; (a2)(b2) microstructures of repair layer at different surface positions at figure-8 swing laser mode; (c1)(d1) microstructures of repair layer at different interface bonding zones at conventional laser mode; (c2)(d2) microstructures of repair layer at different interface bonding zones at figure-8 swing laser mode

Fig. 11. XRD of repair layer at different laser modes. (a) XRD patterns; (b) XRD local amplification

Fig. 12. EDS line scanning analysis of repair layer and ternary alloy phase diagram. (a) Schematic showing line scanning from the surface to the inside of the repair layer; (b) schematic showing horizontal line scanning of the repair layer at the same depth; (c) Fe and Cr elements distribution from the surface to the inside of the conventional laser repair layer; (d) Fe and Cr elements distribution from the surface to the inner of the figure-8 swing laser repair layer; (e) Fe and Cr elements distribution at the same depth of the conventional laser repair layer; (f) Fe and Cr elements distribution of at the same depth of the figure-8 swing laser repair layer; (g) phase diagram of Fe‒Cr‒C ternary alloy^[30]

Fig. 13. Contour maps showing surface microhardness of different laser repair layers and the substrate. (a) Conventional laser repair layer; (b) figure-8 swing laser repair layer; (c) substrate

Fig. 14. Microhardness of the transverse and longitudinal sections of different laser repair layers at the same depth. (a) Transverse section; (b) longitudinal section

Fig. 15. Microhardness of different laser repair layers from inside to outside

Fig. 16. Friction coefficient, wear loss, wear profile and wear rate of different repair layers. (a) Friction coefficient; (b) wear loss; (c) wear profile; (d) wear rate

Fig. 17. Wear trace of different repair layers. (a) Conventional laser repair layer; (b) figure-8 swing laser repair layer; (c) substrate

Fig. 18. Affecting mechanism of different laser modes on microhardness uniformity of repair layer. (a) Conventional laser; (b) figure-8 swing laser