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

modify the microstructure and enhance the properties of Researchers have proposed various theoretical
LMD titanium alloys. studies and numerical models to clarify the effect of
Electromagnetic field treatment has been reported to electromagnetic fields on molten pool dynamics. However,
effectively enhance the microstructure and properties of due to the coupling of multiple physical fields and the
high computational requirements, the development of a
titanium alloys. 13,14 Qin et al. investigated axisymmetric
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sequential and loose electromagnetic-structural coupling more comprehensive and accurate 3D numerical model
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simulation models of the electromagnetic riveting process for electromagnetic field coupling in LMD is warranted.
for a Ti-6Al-4V titanium rivet. The results indicated that Research on in situ manipulation of LMD of Ti-6Al-4V
increasing the displacement of the punch from 3.38 to titanium alloy using an electromagnetic field has rarely
been reported in recent years. Different materials respond
3.81 mm led to an 80.55% increase in the maximum radial differently to electromagnetic fields, which in turn affect
displacement of the rivet shaft. Li et al. investigated
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the effect of an alternating electromagnetic field on the deposition process parameters, molten pool flow behavior,
microstructure and properties of the Ti-Al coating on the and cooling rates, ultimately influencing the microstructure
and properties of the deposition layer. Hence, conducting
titanium alloy surface; the results demonstrated that the experimental and simulation research on the in situ
coating diffused under the magnetic field with a current manipulation of the LMD process for Ti-6Al-4V titanium
intensity of 20 A and displayed good overall quality, strong alloy using electromagnetic fields is of great significance.
bonding with the substrate, a relatively flat interface, a dense
and uniform fine structure, and no obvious cracks or holes. 2. Methods
Song et al. investigated the effect of cryogenic coupled
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magnetic field (CCMF) treatment on the microstructure 2.1. Numerical model for LMD
and mechanical properties of Ti-6Al-4V titanium alloy 2.1.1. Geometric model
and found that the CCMF-treated samples displayed a A 3D numerical model was utilized to study the size and
lower ultimate tensile strength but a higher elongation morphology of the deposition layer, as well as the flow
compared to samples that underwent either single behavior of the molten pool. However, the approach
cryogenic treatment or single magnetic treatment. Hence, resulted in a higher computational load. The symmetrical
studying the in situ manipulation of the microstructure and model with half of the computational domain in the
properties of LMD titanium alloy using an electromagnetic x-direction was used. The schematic of the geometric
field is of great significance.
model is illustrated in Figure 1.The dimension of the
An electromagnetic field primarily influences the geometric model is 5 × 15 × 10 mm; the upper blue area
microstructure of materials by inducing electromagnetic represents the argon environment, whereas the lower gray
forces within the molten pool. The transfer and convection area represents the Ti-6Al-4V substrate (Figure 1A). The
of heat in the molten pool are regulated by the parameters geometric model was divided into six regions to optimize
and direction of the electromagnetic field, temperature the calculation while maintaining the accuracy of the
gradient, and flow pattern during metal solidification. The molten pool area. Local mesh refinement was applied in
effect of an electromagnetic field in LMD is dependent on its the molten pool area, as depicted by the light blue and
ability to suppress convection in the molten pool. Bachmann gray areas (Figure 1A). A hexahedral structured mesh was
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et al. developed a 3D welding molten pool model with used to divide the geometric model (Figure 1B), where
an applied electromagnetic field, where the direction of the yellow surface represents the symmetry plane of the
the steady electromagnetic field was perpendicular to model. The five interfaces of the argon gas domain in the
the welding direction. The steady electromagnetic field model are pressure outlets, and the mesh size of the locally
could alter the molten pool flow pattern, affect the weld refined molten pool area is 0.1 mm. The scanning direction
geometry, and consequently impact welding quality by of the LMD is in the positive y-axis direction.
suppressing convection within the molten pool. Velde
et al. conducted a numerical study on the development 2.1.2. Basic assumptions of the numerical simulation
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process of the aluminum molten pool under the influence model
of a steady electromagnetic field of different strengths The following assumptions were made when establishing
during LMD. The researchers demonstrated that a the multiphase model coupled with the electromagnetic
steady electromagnetic field can suppress eddy currents, field:
effectively mitigating the uneven temperature distribution (i) The liquid metal in the molten pool during the LMD
resulting from unstable convection, thereby improving the process is assumed to be an incompressible Newtonian
material properties. fluid, and the flow regime is laminar 21

Volume 4 Issue 1 (2025) 2 doi: 10.36922/msam.8332