Page 36 - MSAM-4-3

Materials Science in Additive Manufacturing Numerical simulation of plasma WAAM for Ti-6Al-4V

experimental observations. Recent studies, such as Liu along its designated path, initiating the cooling phase.
et al. and Bai et al., have shown that the inclusion of Cooling rates are inversely proportional to the distance
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fluid flow dynamics within the melt pool can provide a from the heat source, with temperature profiles flattening
more comprehensive representation of thermal and fluid as heat dissipation progresses. These observations are
behavior. consistent with recent experimental and computational
studies on WAAM thermal modeling. 16,35
3.2.2. Thermal profiles
In particular, the simulated and experimental heating
The thermal models are validated by comparing simulated and cooling rates are in good agreement, confirming
and experimental temperature histories. Figure 6 shows the accuracy of the FE framework. However, the peak
the temperature evolution of single-bead deposition, temperatures predicted by the model are slightly higher
pre-heating, and single-bead deposition with preceding than the experimental measurements. A possible
pre-heating at each thermocouple TC1, TC2, and TC3. explanation for this deviation is the measurement lag
Depending on the distance from the heat source, different due to the thermocouple response time (0.9 s) and data
temperature–time curves are obtained. acquisition frequency (1 s), which limits the ability of
For single bead deposition (Figure 6A), the temperature the measurement system to accurately capture rapid
peaks decrease with increasing distance from the weld path, thermal transients, especially when the heat source passes
confirming the expected spatial thermal gradients. Once through the thermocouple locations. Similar challenges
the peak temperature is reached, the heat source moves were reported by Aarbogh et al., who observed peak
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A B

C

Figure 6. Overview and comparison of experimental (dotted line) and simulated (solid line) temperature profiles at various thermocouple locations
obtained during (A) single bead deposition, (B) pre-heating, and (C) single bead deposition plus pre-heating. Thermocouples (TC) were positioned at
pre-defined lateral and longitudinal distances relative to the weld track to capture the transient thermal behavior during deposition. Specifically, TC1 was
placed at 8 mm, TC2 at 9 mm, and TC3 at 10 mm laterally from the weld centerline. In the welding direction, the thermocouples TC1 to TC3 have an
offset of 5 mm.

Volume 4 Issue 3 (2025) 9 doi: 10.36922/MSAM025140021