Fig. 1. Schematic of welding experiment

Fig. 2. Schematic of (a) groove and (b) filling sequence

Fig. 3. Size of tensile sample

Fig. 4. Macromorphology of welding joint

Fig. 5. Zone distributions of welding joint. (a) Root face; (b) filler pass

Fig. 6. Microstructures of WSZ and BM of welding joint. (a) WSZ of root-face pass; (b) NRZ of filler pass; (c) RZ of filler pass; (d) BM

Fig. 7. Microstructures of HAZ. (a) CFZ of root-face pass; (b) FGZ of root-face pass; (c) TZ of root-face pass; (d) CFZ of filler pass; (e) FGZ of filler pass; (f) TZ of filler pass

Fig. 8. Microhardness distributions of welding joint at different positions

Fig. 9. Tensile test. (a) Macrophoto of tensile sample; (b) tensile test results

Fig. 10. Microstructures of impact fracture at WSZ of welding joint. (a) Root-face pass; (b) partially enlarged view of position 1 in Fig. 10(a); (c) partially enlarged view of position 2 in Fig. 10(a); (d) filler pass; (e) partially enlarged view of position 3 in Fig. 10(d); (f) partially enlarged view of position 4 in Fig. 10(d)