Fig. 1. Wobble modes of laser beam

Fig. 2. Groove dimension of narrow gap laser welding for TC4 titanium alloy

Fig. 3. Diagram of protective atmosphere mask

Fig. 4. Effect of oscillation modes on weld formation

Fig. 5. Effect of oscillation amplitude on weld formation

Fig. 6. Effect of oscillation frequency on weld formation

Fig. 7. Effect of oscillation parameters on width and depth of fusion and form factor of weld. (a) Oscillation modes; (b) oscillation amplitude; (c) oscillation frequency

Fig. 8. Effect of oscillation parameters on porosity. (a) Oscillation modes; (b) oscillation amplitude; (c) oscillation frequency

Fig. 9. X-ray films with different oscillation frequencies. (a) 20 Hz; (b) 60 Hz ; (c) 100 Hz; (d) 150 Hz; (e) 200 Hz

Fig. 10. Groove dimension of narrow gap welding for 20 mm TC4 titanium alloy

Fig. 11. Morphology and macrostructure of 20 mm TC4 titanium alloy narrow gap joint. (a) Front; (b) back; (c) cross section

Fig. 12. X-ray film of 20 mm TC4 titanium alloy joint

Fig. 13. Tensile sampling position, fracture location, and fracture morphology. (a) Sampling position; (b) fracture location; (c) fracture morphology 50×; (d) fracture morphology 1000×