Stabilising mechanism of cathode jet and droplet transfer in hybrid-laser–GMAW-based directed energy deposition of titanium alloy

Figures & data

Figure 1. (a) Diagram of hybrid laser–GMAW-based DED; (b) High-speed photography system; (c) Spectral information acquisition system.

Table 1. Chemical compositions of Ti6Al4 V base metal and wire.

	Ti	Al	V	Fe	C	N	H	O
Base metal	Bal	5.90	4.10	0.09	0.02	0.01	0.003	0.09
Wire	Bal	6.10	4.01	0.15	0.016	0.05	0.015	0.15

Figure 2. The macroscopic images of: (a) GMAW-based DED; (b) Hybrid-laser–GMAW-based DED.

Table 2. Statistical results of forming quality.

	K/ %	$\overline{\mathit{S}}$ (mm)	xmin	xmax
GMAW	69	0.32	6.8 mm	9.8 mm
Hybrid	80	0.29	7.2 mm	9.0 mm

Figure 3. Process flow for calculating arc temperature using the Fowler–Milne method.

Figure 4. Electrical signal waveform and arc image of GMAW-based DED.

Figure 5. Electrical signal waveform and arc image of hybrid laser–GMAW-based DED.

Figure 6. Spatial distributions of Ti Ⅰ and Ti Ⅱ particles.

Figure 7. Dynamic droplet transfer behaviours.

Figure 8. (a) Temperatures for thermionic emission at various current density levels [33]; (b) Current density of thermionic emission varies with temperature for various materials

Figure 9. Numerical result of the molten pool in hybrid-laser–GMAW-based DED.

Figure 10. Schematic of cathode jet generation.

Figure 11. Plasma temperature: (a) calculated arc temperature in GMAW-based DED using the Fowler–Milne method; (b) validation using the Boltzmann plot method.

Figure 12. (a) Equilibrium composition of Ar-50 at%Ti; (b) Relationship curve between critical temperature and equilibrium composition.

Figure 13. (a) Statistics of droplet growth time, droplet transfer time and cathode jet angle; (b) Statistics of spatter number per layer in DED; (c) Schematic diagram of force analysis.

Figure 14. Summarisation of the laser effects.

Guile AE. Arc-electrode phenomena. In Proceedings of the Institution of Electrical Engineers (Vol. 118, No. 9R). IET Digital Library; 1971. pp. 1131–1154.

 Google Scholar

Data availability statement

The data that support the findings of this study are available from the corresponding author, [Dongshen Wu], upon reasonable request.