Fig. 1. Profile of single groove in laser-arc hybrid welding

Fig. 2. Schematic of distance between laser spot and wire tip

Fig. 3. Profiles of laser and arc plasma at different moments with d＝2 mm. (a) t＝0 s; (b) t＝0.01 s; (c) t＝0.02 s; (d) t＝0.03 s; (e) t＝3.01 s; (f) t＝3.02 s; (g) t＝3.03 s; (h) t＝3.04 s

Fig. 4. Profiles of laser and arc plasma at different moments with d＝4 mm. (a) t＝0 s; (b) t＝0.01 s; (c) t＝0.02 s; (d) t＝0.03 s; (e) t＝3.01 s; (f) t＝3.02 s; (g) t＝3.03 s; (h) t＝3.04 s

Fig. 5. Profiles of laser and arc plasma at different moments with d＝6 mm. (a) t＝0 s; (b) t＝0.01 s；(c) t＝0.02 s; (d) t＝0.03 s; (e) t＝3.01 s; (f) t＝3.02 s; (g) t＝3.03 s; (h) t＝3.04 s

Fig. 6. Dynamic characters of molten pool at different moments with d＝2 mm. (a) t＝0 s; (b) t＝0.1 s; (c) t＝0.2 s; (d) t＝0.3 s; (e) t＝3.1 s; (f) t＝3.2 s; (g) t＝3.3 s; (h) t＝3.4 s

Fig. 7. Dynamic characters of molten pool at different moments with d＝4 mm. (a) t＝0 s；(b) t＝0.1 s；(c) t＝0.2 s；(d) t＝0.3 s；(e) t＝3.1 s；(f) t＝3.2 s；(g) t＝3.3 s；(h) t＝3.4 s

Fig. 8. Dynamic characters of molten pool at different moments with d＝6 mm. (a) t＝0 s; (b) t＝0.1 s; (c) t＝0.2 s; (d) t＝0.3 s; (e) t＝3.1 s; (f) t＝3.2 s; (g) t＝3.3 s; (h) t＝3.4 s

Fig. 9. Coupling mechanism of laser and arc plasma at the groove with d＝4 mm. (a) Coupling at the bottom of groove at the beginning of welding; (b) coupling separation due to the increase of liquid level in arc zone; (c) coupling due to molten pool level fluctuation; (d) coupling separation due to liquid level difference between laser zone and arc zone

Fig. 10. Profiles of welding surface and cross section under different arc tip and laser distances (P＝7 kW, I＝240 A, and v＝0.5 m/min). (a) d＝2 mm; (b) d＝4 mm; (c) d＝6 mm