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Materials Science in Additive Manufacturing In situ electromagnetic field manipulation during LMD

and 0.31 µm, respectively. This width is reduced when the (iv) The effect mechanisms of the Lorentz force induced
electromagnetic field intensity is 39.40 mT. The uniformity by electromagnetic field include the directional flow
of hardness distribution in the molten pool area is the most velocity in the molten pool becoming disordered under
obvious, indicating enhanced uniformity of the surface the influence of the Lorentz force, interfering with grain
structure. In addition, it can be observed that the hardness growth and refinement; and the restraining effect of the
in the molten pool of samples EM-1 (Figure 13B), EM-2 Lorentz force on the molten pool flow that reduced the
(Figure 13C), and EM-3 (Figure 13D) increased with the cooling rate, thereby promoting grain growth.
effect of electromagnetic field compared to sample EM-0
(Figure 13A). Based on the above results, it can be concluded that
the in situ manipulation of the electromagnetic field via
The F exhibits an inhibitory effect on the flow of the Lorentz force during LMD is significant, offering a novel
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molten pool after the introduction of an electromagnetic and effective approach for controlling the microstructure
field, which reduces heat dissipation and increases the and mechanical properties of titanium alloys.
maximum temperature. Further precipitation of the
α-phase was observed in samples EM-1 (Figure 7J), Acknowledgments
EM-2 (Figure 8D), and EM-3 (Figure 8J) during cooling None.
compared to EM-0 (Figure 7D), increasing the overall
hardness. Due to the disordered molten pool flow caused Funding
by F in sample EM-1, thermal radiation spreads evenly,
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resulting in a consistent microstructure. The decreased This work was financially supported by the Major Research
cooling rate caused by F in samples EM-2 and EM-3 leads Plan of the National Natural Science Foundation of
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to the observed differences in microstructure, i.e., long China (Grant No. 92266102), National Natural Science
columnar grain in EM-2 (Figure 3C) and coarse grain in Foundation of China (No. 52271135), Innovation Funding
EM-3 (Figure 3D). Project of National Engineering and Research Center
for Commercial Aircraft Manufacturing (COMAC-
4. Conclusion SFGS-2022-1871), Overseas Expertise Introduction
This study investigated the effect of in situ manipulation Project for Discipline Innovation (B17034), and Innovative
of the electromagnetic field on the microstructure Research Team Development Program of Ministry of
and hardness of titanium alloy during LMD. The Education of China (IRT_17R83).
microstructure, texture orientation, and hardness of the Conflicts of interest
Ti-6Al-4V alloy were investigated via a combination of
experiments and numerical simulation. The key findings Both Lechun Xie and Liqiang Wang serve as the Editorial
are summarized as follows: Board Members of the journal but were not involved in any
(i) The width, height, and melt depth of the deposition way (directly or indirectly) in the editorial and peer-review
layer were significantly reduced under the process conducted for this paper. Other authors declare
electromagnetic field. The electromagnetic field they have no competing interests.
inhibits the heat transfer and mass transport flow
from the center of the laser beam to the surroundings, Author contributions
thereby reducing the size of the molten pool Conceptualization: Lechun Xie, Yan Wen
(ii) The numerical simulation results indicated that Data curation: Chang Liu, Yongjian Wu
the maximum flow velocity in the molten pool was Investigation: Chang Liu, Yongjian Wu
0.58 m/s without the electromagnetic field, whereas Methodology: Lechun Xie
the maximum flow velocity in the molten pool region Supervision: Lechun Xie
was 0.41 m/s under an electromagnetic field intensity Writing - original draft: Chang Liu, Yongjian Wu
of 39.40 mT; i.e., a 29% decrease. In addition, the Writing - review & editing: Jian Zhou, Yan Wen, Liqiang
velocity vector of the molten pool flow distribution Wang, Lechun Xie
became disordered
(iii) The average length of β-grains was 490 μm without Ethics approval and consent to participate
the electromagnetic field, which was decreased to
354 μm under an electromagnetic field intensity of Not applicable
39.40 mT. The elongated large β-columnar grains were Consent for publication
also observed with increasing electromagnetic field
intensity Not applicable.

Volume 4 Issue 1 (2025) 16 doi: 10.36922/msam.8332