Numerical analyses of molten pool evolution in laser polishing Ti6Al4V

Li, Kai; Zhao, Zhenyu; Zhou, Houming; Jin, Jingcheng

doi:10.1016/j.jmapro.2020.08.045

Cited by 49 publications

(25 citation statements)

References 24 publications

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“…It can be observed that the maximum velocity can reach 1.8 m/s in the molten pool during laser polishing. Li et al [ 29 ] found that the surface tension and Marangoni flow played key roles in smoothing the surface during laser polishing Ti–6Al–4V. In this paper, due to Marangoni flow and surface tension, the rough surface moves into the tail region of the molten pool.…”

Section: Mathematical Modelingmentioning

confidence: 79%

In-Situ Laser Polishing Additive Manufactured AlSi10Mg: Effect of Laser Polishing Strategy on Surface Morphology, Roughness and Microhardness

Zhou

Han

et al. 2021

Materials

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Laser polishing is a widely used technology to improve the surface quality of the products. However, the investigation on the physical mechanism is still lacking. In this paper, the established numerical transient model reveals the rough surface evolution mechanism during laser polishing. Mass transfer driven by Marangoni force, surface tension and gravity appears in the laser-induced molten pool so that the polished surface topography tends to be smoother. The AlSi10Mg samples fabricated by laser-based powder bed fusion were polished at different laser hatching spaces, passes and directions to gain insight into the variation of the surface morphologies, roughness and microhardness in this paper. The experimental results show that after laser polishing, the surface roughness of Ra and Sa of the upper surface can be reduced from 12.5 μm to 3.7 μm and from to 29.3 μm to 8.4 μm, respectively, due to sufficient wetting in the molten pool. The microhardness of the upper surface can be elevated from 112.3 HV to 176.9 HV under the combined influence of the grain refinement, elements distribution change and surface defects elimination. Better surface quality can be gained by decreasing the hatching space, increasing polishing pass or choosing apposite laser direction.

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Section: Mathematical Modelingmentioning

confidence: 79%

In-Situ Laser Polishing Additive Manufactured AlSi10Mg: Effect of Laser Polishing Strategy on Surface Morphology, Roughness and Microhardness

Zhou

Han

et al. 2021

Materials

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“…Figure 3c shows that the surface of silicon wafer melts during laser grinding. Molten silicon is redistributed in flow due to the simultaneous action of surface tension and Maragani effect [20]. The mechanism of laser grinding includes two steps, which are shown in Figure 3a,b.…”

Section: Effect Of Laser Grinding On Surface Morphologymentioning

confidence: 99%

Laser Grinding of Single-Crystal Silicon Wafer for Surface Finishing and Electrical Properties

Wang

2021

Micromachines

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In this paper, we first report the laser grinding method for a single-crystal silicon wafer machined by diamond sawing. 3D laser scanning confocal microscope (LSCM), X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), laser micro-Raman spectroscopy were utilized to characterize the surface quality of laser-grinded Si. Results show that SiO2 layer derived from mechanical machining process has been efficiently removed after laser grinding. Surface roughness Ra has been reduced from original 400 nm to 75 nm. No obvious damages such as micro-cracks or micro-holes have been observed at the laser-grinded surface. In addition, laser grinding causes little effect on the resistivity of single-crystal silicon wafer. The insights obtained in this study provide a facile method for laser grinding silicon wafer to realize highly efficient grinding on demand.

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“…In this paper, the model is based on the energy equation (Equation ( 1)), momentum equation (Equation ( 2)) and continuity equation (Equation ( 3)) as the theoretical guidance [22][23][24][25][26].…”

Section: Governing Equationsmentioning

confidence: 99%

“…where C p is the specific heat, L m is the latent heat of melting, the definition of liquid fraction f L as follow [22][23][24][25][26]…”

Section: Governing Equationsmentioning

confidence: 99%

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Numerical Simulation of Effect of Different Initial Morphologies on Melt Hydrodynamics in Laser Polishing of Ti6Al4V

Zhao

Zhou

et al. 2021

Micromachines

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As a surface finishing technique for rapid remelting and re-solidification, laser polishing can effectively eliminate the asperities so as to approach the feature size. Nevertheless, the polished surface quality is significantly sensitive to the processing parameters, especially with respect to melt hydrodynamics. In this paper, a transient two-dimensional model was developed to demonstrate the molten flow behavior for different surface morphologies of the Ti6Al4V alloy. It is illustrated that the complex evolution of the melt hydrodynamics involving heat conduction, thermal convection, thermal radiation, melting and solidification during laser polishing. Results show that the uniformity of the distribution of surface peaks and valleys can improve the molten flow stability and obtain better smoothing effect. The high cooling rate of the molten pool resulting in a shortening of the molten lifetime, which prevents the peaks from being removed by capillary and thermocapillary forces. It is revealed that the mechanism of secondary roughness formation on polished surface. Moreover, the double spiral nest Marangoni convection extrudes the molten to the outsides. It results in the formation of expansion and depression, corresponding to nearby the starting position and at the edges of the polished surface. It is further found that the difference between the simulation and experimental depression depths is only about 2 μm. Correspondingly, the errors are approximately 8.3%, 14.3% and 13.3%, corresponding to Models 1, 2 and 3, respectively. The aforementioned results illustrated that the predicted surface profiles agree reasonably well with the experimentally measured surface height data.

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Numerical analyses of molten pool evolution in laser polishing Ti6Al4V

Cited by 49 publications

References 24 publications

In-Situ Laser Polishing Additive Manufactured AlSi10Mg: Effect of Laser Polishing Strategy on Surface Morphology, Roughness and Microhardness

In-Situ Laser Polishing Additive Manufactured AlSi10Mg: Effect of Laser Polishing Strategy on Surface Morphology, Roughness and Microhardness

Laser Grinding of Single-Crystal Silicon Wafer for Surface Finishing and Electrical Properties

Numerical Simulation of Effect of Different Initial Morphologies on Melt Hydrodynamics in Laser Polishing of Ti6Al4V

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