Fig. 1. Morphology and size of 30CrMnSiA alloy powders. (a) SEM morphology; (b) particle size distribution

Fig. 2. Schematics of laser-cladding and sampling of mechanical properties test samples. (a) Substrate with notch for lase cladding; (b) diagram of laser-cladding; (c) laser scanning pattern; (d) sampling method of mechanical properties test samples

Fig. 3. Schematics of tensile samples and impact samples. (a) Impact sample; (b) tensile sample

Fig. 4. Cross-section macroscopic morphology of two high-strength steels after multi-layer laser-cladding. (a) 30CrMnSiA substrate; (b) HAZ on 30CrMnSiA substrate; (c) 30CrMnSiNi2A substrate; (d) HAZ on 30CrMnSiNi2A substrate

Fig. 5. Microstructures of two high-strength steel substrates and HAZ. (a) 30CrMnSiA substrate; (b) HAZ on 30CrMnSiA substrate; (c) 30CrMnSiNi2A substrate; (d) HAZ on 30CrMnSiNi2A substrate

Fig. 6. Microstructures of different cladding layers on 30CrMnSiA substrate. (a) The first layer; (b) the second layer; (c) the third layer; (d) the fourth layer; (e) the fifth layer; (f) the sixth layer (cap layer)

Fig. 7. Microstructures of different cladding layers on 30CrMnSiNi2A substrate. (a) The first layer; (b) the second layer; (c) the third layer; (d) the fourth layer; (e) the fifth layer; (f) the sixth layer (cap layer)

Fig. 8. Metallography image and microhardness distribution in cross-section of cladding samples on two high strength steel substrates. (a) 30CrMnSiA, metallography image; (b) 30CrMnSiNi2A, metallography image; (c) 30CrMnSiA, microhardness distribution; (d) 30CrMnSiNi2A, microhardness distribution

Fig. 9. Mechanical properties of two substrates and cladding samples at room-temperature. (a) Impact toughness; (b) tensile property

Fig. 10. Impact fracture morphologies of cladding samples on different substrates. (a)(c) Fracture of cladding sample on 30CrMnSiA substrate and partially enlarged crack source; (c)(d) fracture of cladding sample on 30CrMnSiNi2A substrate and partially enlarged crack source

Fig. 11. Tensile fracture in cross-section of cladding sample on 30CrMnSiA substrate. (a) Cross-section image; (b)--(d) partially enlarged images

Fig. 12. Tensile fracture in cross-section of cladding sample on 30CrMnSiNi2A substrate. (a) Cross-section image; (b)--(d) partially enlarged images