Journal articles: 'Melt pool convection'

1

Das, Saurabh, and Satya Prakash Kar. "Role of Marangoni Convection in a Repetitive Laser Melting Process." Materials Science Forum 978 (February 2020): 34–39. http://dx.doi.org/10.4028/www.scientific.net/msf.978.34.

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To effectively interpret the fluid flow dynamics in the molten metal pool, a numerical model was established. The moving repetitive Gaussian laser pulse is irradiated in the work piece. The consideration of laser scanning speed makes the transport phenomena complex. The continuity and momentum equations are solved to get the flow velocity of the molten metal in the melt pool. The energy equation is solved to know the temperature field in the work piece. The algebraic equations obtained after discretization of the governing equations by Finite Volume Method (FVM) are then solved by the Tri Diagonal Matrix Method. Enthalpy-porosity technique is used to capture the position of the melt front which determines the shape of the melt pool. Marangoni convection is considered to know its effect on the shape of the melt pool. The surface tension coefficient is taken as both positive and negative value while calculating the Marangoni force. The two possible cases will cause the Marangoni force to distort the flow dynamics in the melt pool . It's dominance over the buoyancy force in controlling the melt pool shape is focused in the present study. Further, the present model will present an insight to the consequences of laser scanning velocity over the melt pool dimensions and shape.

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Jähnig, Theresa, Cornelius Demuth, and Andrés Fabián Lasagni. "Influence of Sulphur Content on Structuring Dynamics during Nanosecond Pulsed Direct Laser Interference Patterning." Nanomaterials 11, no. 4 (March 27, 2021): 855. http://dx.doi.org/10.3390/nano11040855.

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The formation of melt and its spread in materials is the focus of many high temperature processes, for example, in laser welding and cutting. Surface active elements alter the surface tension gradient and therefore influence melt penetration depth and pool width. This study describes the application of direct laser interference patterning (DLIP) for structuring steel surfaces with diverse contents of the surface active element sulphur, which affects the melt convection pattern and the pool shape during the process. The laser fluence used is varied to analyse the different topographic features that can be produced depending on the absorbed laser intensity and the sulphur concentration. The results show that single peak geometries can be produced on substrates with sulphur contents lower than 300 ppm, while structures with split peaks form on higher sulphur content steels. The peak formation is explained using related conceptions of thermocapillary convection in weld pools. Numerical simulations based on a smoothed particle hydrodynamics (SPH) model are employed to further investigate the influence of the sulphur content in steel on the melt pool convection during nanosecond single-pulsed DLIP.

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Wei, P. S., H. J. Liu, and C. L. Lin. "Scaling weld or melt pool shape induced by thermocapillary convection." International Journal of Heat and Mass Transfer 55, no. 9-10 (April 2012): 2328–37. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2012.01.034.

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4

Wei, Hongyang, Yi-Tung Chen, and Jie Cheng. "Review of experimental study on melt pool natural convection behavior." Annals of Nuclear Energy 122 (December 2018): 101–17. http://dx.doi.org/10.1016/j.anucene.2018.08.008.

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Han, Lijun, Frank W. Liou, and Srinivas Musti. "Thermal Behavior and Geometry Model of Melt Pool in Laser Material Process." Journal of Heat Transfer 127, no. 9 (April 25, 2005): 1005–14. http://dx.doi.org/10.1115/1.2005275.

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Melt pool geometry and thermal behavior control are essential in obtaining consistent building performances, such as geometrical accuracy, microstructure, and residual stress. In this paper, a three dimensional model is developed to predict the thermal behavior and geometry of the melt pool in the laser material interaction process. The evolution of the melt pool and effects of the process parameters are investigated through the simulations with stationary and moving laser beam cases. The roles of the convection and surface deformation on the heat dissipation and melt pool geometry are revealed by dimensionless analysis. The melt pool shape and fluid flow are considerably affected by interfacial forces such as thermocapillary force, surface tension, and recoil vapor pressure. Quantitative comparison of interfacial forces indicates that recoil vapor pressure is dominant under the melt pool center while thermocapillary force and surface tension are more important at the periphery of the melt pool. For verification purposes, the complementary metal oxide semiconductor camera has been utilized to acquire the melt pool image online and the melt pool geometries are measured by cross sectioning the samples obtained at various process conditions. Comparison of the experimental data and model prediction shows a good agreement.

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6

Li, Yourong, Lan Peng, Shuangying Wu, and Nobuyuki Imaishi. "Bifurcation of thermocapillary convection in a shallow annular pool of silicon melt." Acta Mechanica Sinica 23, no. 1 (January 6, 2007): 43–48. http://dx.doi.org/10.1007/s10409-006-0053-2.

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7

Shi, Wanyuan, You-Rong Li, Michael K. Ermakov, and Nobuyuki Imaishi. "Stability of Thermocapillary Convection in Rotating Shallow Annular Pool of Silicon Melt." Microgravity Science and Technology 22, no. 3 (April 24, 2010): 315–20. http://dx.doi.org/10.1007/s12217-010-9194-9.

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8

Fan, T. H., and F. B. Cheung. "Modeling of Transient Turbulent Natural Convection in a Melt Layer With Solidification." Journal of Heat Transfer 119, no. 3 (August 1, 1997): 544–52. http://dx.doi.org/10.1115/1.2824137.

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The phenomenon of turbulent natural convection in a horizontal heat-generating melt layer with solidification taking place at the cooled upper and lower boundaries is investigated theoretically. The objective is to determine the transient behavior of the crust at the upper and lower surfaces and the effect of crust formation on the turbulent natural convection process in the melt layer. Various surface temperatures, latent heats, and the heat source strengths are considered along with the effects of the Stefan number and Rayleigh number. Special attention is given to the interaction between the melt pool heat transfer and the crust dynamics. Numerical results are presented for the transient crust thickness, transient temperature distribution, eddy heat transport, and the heat transfer characteristics at the solid-liquid interface during the freezing process. The present study provides basic information needed to predict the transient behavior of a melt pool in a reactor lower head following a severe core-meltdown accident.

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9

Demuth, Cornelius, and Andrés Fabián Lasagni. "An Incompressible Smoothed Particle Hydrodynamics (ISPH) Model of Direct Laser Interference Patterning." Computation 8, no. 1 (January 30, 2020): 9. http://dx.doi.org/10.3390/computation8010009.

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Functional surfaces characterised by periodic microstructures are sought in numerous technological applications. Direct laser interference patterning (DLIP) is a technique that allows the fabrication of microscopic periodic features on different materials, e.g., metals. The mechanisms effective during nanosecond pulsed DLIP of metal surfaces are not yet fully understood. In the present investigation, the heat transfer and fluid flow occurring in the metal substrate during the DLIP process are simulated using a smoothed particle hydrodynamics (SPH) methodology. The melt pool convection, driven by surface tension gradients constituting shear stresses according to the Marangoni boundary condition, is solved by an incompressible SPH (ISPH) method. The DLIP simulations reveal a distinct behaviour of the considered substrate materials stainless steel and high-purity aluminium. In particular, the aluminium substrate exhibits a considerably deeper melt pool and remarkable velocity magnitudes of the thermocapillary flow during the patterning process. On the other hand, convection is less pronounced in the processing of stainless steel, whereas the surface temperature is consistently higher. Marangoni convection is therefore a conceivable effective mechanism in the structuring of aluminium at moderate fluences. The different character of the melt pool flow during DLIP of stainless steel and aluminium is confirmed by experimental observations.

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10

Li, You-Rong, Xin-Xing Zhao, Shuang-Ying Wu, and Lan Peng. "Asymptotic solution of thermocapillary convection in a thin annular pool of silicon melt." Physics of Fluids 20, no. 8 (August 2008): 082107. http://dx.doi.org/10.1063/1.2975172.

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11

Picasso, M., and A. F. A. Hoadley. "Finite element simulation of laser surface treatments including convection in the melt pool." International Journal of Numerical Methods for Heat & Fluid Flow 4, no. 1 (January 1994): 61–83. http://dx.doi.org/10.1108/eum0000000004031.

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12

Kumar, Amitesh, and Subhransu Roy. "Effect of three-dimensional melt pool convection on process characteristics during laser cladding." Computational Materials Science 46, no. 2 (August 2009): 495–506. http://dx.doi.org/10.1016/j.commatsci.2009.04.002.

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13

Tan, M. J., D. H. Cho, and F. B. Cheung. "Thermal Analysis of Heat-Generating Pools Bounded From Below by Curved Surfaces." Journal of Heat Transfer 116, no. 1 (February 1, 1994): 127–35. http://dx.doi.org/10.1115/1.2910846.

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A computer code that features the use of a directional effective thermal conductivity in modeling natural convection in heat-generating pools has been developed to analyze heat transfer in such pools, which are bounded from below by curved surfaces. Illustrative calculations pertaining to two published experimental studies on convective heat transfer in water pools with uniformly distributed volumetric energy sources are carried out using the code. The water pools used in the two studies under consideration were cooled either from the top or from the bottom, but not from both. The utility as well as the limitations of the effective thermal conductivity approach in the context of addressing the issue of melt-pool coolability is demonstrated by comparisons of calculated results with the experimental data.

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14

Janicki, Damian. "Effect of Chromium and Molybdenum Addition on the Microstructure of In Situ TiC-Reinforced Composite Surface Layers Fabricated on Ductile Cast Iron by Laser Alloying." Materials 13, no. 24 (December 16, 2020): 5750. http://dx.doi.org/10.3390/ma13245750.

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In situ TiC-reinforced composite surface layers (TRLs) were produced on a ductile cast iron substrate by laser surface alloying (LA) using pure Ti powder and mixtures of Ti-Cr and Ti-Mo powders. During LA with pure Ti, the intensity of fluid flow in the molten pool, which determines the TRL’s compositional uniformity, and thus Ti content in the alloyed zone, was directly affected by the fraction of synthesized TiC particles in the melt—with increasing the TiC fraction, the convection was gradually reduced. The introduction of additional Cr or Mo powders into the molten pool, due to their beneficial effect on the intensity of the molten pool convection, elevated the Ti concentration in the melt, and, thus, the TiC fraction in the TRL. It was found that the melt enrichment of Cr, in conjunction with non-equilibrium cooling conditions, suppressed the martensitic transformation of the matrix, which lowered the total hardness of the TRL. Moreover, the presence of Cr in the melt (~3 wt%) altered the growth morphology of the synthesized primary TiC precipitates compared with that obtained using pure Ti. The addition of Mo in the melt produced (Ti, Mo)C primary precipitates that exhibited a nonuniform Mo distribution (coring structure). The dissolution of Mo in the primary TiC precipitates did not affect its growth morphology.

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15

Sehgal, B. R., R. R. Nourgaliev, and T. N. Dinh. "Characterization of heat transfer processes in a melt pool convection and vessel-creep experiment." Nuclear Engineering and Design 211, no. 2-3 (February 2002): 173–87. http://dx.doi.org/10.1016/s0029-5493(01)00434-4.

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16

Song, Boxue, Tianbiao Yu, Xingyu Jiang, Liaoyuan Chen, Wenchao Xi, and Chuang Guan. "Evolution and convection mechanism of the melt pool formed by V-groove laser cladding." Optics & Laser Technology 144 (December 2021): 107443. http://dx.doi.org/10.1016/j.optlastec.2021.107443.

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17

Choi, J., L. Han, and Y. Hua. "Modeling and Experiments of Laser Cladding With Droplet Injection." Journal of Heat Transfer 127, no. 9 (March 22, 2005): 978–86. http://dx.doi.org/10.1115/1.2005273.

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Laser aided Directed Material Deposition (DMD) is an additive manufacturing process based on laser cladding. A full understanding of laser cladding is essential in order to achieve a steady state and robust DMD process. A two dimensional mathematical model of laser cladding with droplet injection was developed to understand the influence of fluid flow on the mixing, dilution depth, and deposition dimension, while incorporating melting, solidification, and evaporation phenomena. The fluid flow in the melt pool that is driven by thermal capillary convection and an energy balance at the liquid–vapor and the solid–liquid interface was investigated and the impact of the droplets on the melt pool shape and ripple was also studied. Dynamic motion, development of melt pool and the formation of cladding layer were simulated. The simulated results for average surface roughness were compared with the experimental data and showed a comparable trend.

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18

Sukumar, Siladitya, and Satya Prakash Kar. "Thermal Modeling of Transport Phenomena for a Pulsed Laser Melting Process." Materials Science Forum 978 (February 2020): 114–20. http://dx.doi.org/10.4028/www.scientific.net/msf.978.114.

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Single pulsed laser melting in a cylindrical titanium alloy work piece is studied numerically using an axisymmetric model. Finite volume method and Tri-Diagonal Matrix Algorithm (TDMA) are used for discretization of the energy equation and solving the resulting algebraic equation respectively in order to obtain temperature distribution inside the computational domain. Heat losses from the irradiated surface takes place through convection and radiation and other surfaces are kept insulated. A volumetric and Gaussian laser is irradiated on the work piece. Validation of the present model with the existing literature is done first and the results agree very well. Then, the detailed transport phenomena during the laser melting process is studied using the model. The enthalpy porosity technique is used track the melt pool shape and size. The role of natural convection and Marangoni convection in controlling the shape of melt pool is discussed. Maximum temperature results at domain centre and it then decreases exponentially along the axial and radial direction of the work piece because of Gaussian nature of the pulse. The numerical results obtained can provide the direction to develop models for all type of laser applications used in the industry.

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19

Li, Linmin, Baokuan Li, Lichao Liu, and Yuichi Motoyama. "Numerical Modeling of Fluid Flow, Heat Transfer and Arc–Melt Interaction in Tungsten Inert Gas Welding." High Temperature Materials and Processes 36, no. 4 (April 1, 2017): 427–39. http://dx.doi.org/10.1515/htmp-2016-0120.

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AbstractThe present work develops a multi-region dynamic coupling model for fluid flow, heat transfer and arc–melt interaction in tungsten inert gas (TIG) welding using the dynamic mesh technique. The arc–weld pool unified model is developed on basis of magnetohydrodynamic (MHD) equations and the interface is tracked using the dynamic mesh method. The numerical model for arc is firstly validated by comparing the calculated temperature profiles and essential results with the former experimental data. For weld pool convection solution, the drag, Marangoni, buoyancy and electromagnetic forces are separately validated, and then taken into account. Moreover, the model considering interface deformation is adopted in a stationary TIG welding process with SUS304 stainless steel and the effect of interface deformation is investigated. The depression of weld pool center and the lifting of pool periphery are both predicted. The results show that the weld pool shape calculated with considering the interface deformation is more accurate.

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20

Zhang, Quan-Zhuang, Lan Peng, Fei Wang, and Jia Liu. "Thermocapillary convection with bidirectional temperature gradients in a shallow annular pool of silicon melt: Effects of ambient temperature and pool rotation." International Journal of Heat and Mass Transfer 101 (October 2016): 354–64. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2016.05.015.

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21

Chan, C. L., J. Mazumder, and M. M. Chen. "Effect of surface tension gradient driven convection in a laser melt pool: Three‐dimensional perturbation model." Journal of Applied Physics 64, no. 11 (December 1988): 6166–74. http://dx.doi.org/10.1063/1.342121.

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22

Chang, Qing Ming, Jing Yuan, Yin Kai Yang, Xia Chen, Chang Jun Chen, and Si Qian Bao. "Numerical Study on Laser Cladding of BT20 Alloy." Advanced Materials Research 479-481 (February 2012): 850–53. http://dx.doi.org/10.4028/www.scientific.net/amr.479-481.850.

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A 3-D modeling based on the numerical resolution of fluid flow and heat transfer are utilized to investigate the thermal phenomena during laser laser-cladding processes of BT20 alloy. From this model, it has been found that the shape and size of the molten pool in the work piece are affected by laser cladding parameters such as scanning speed and the incident laser power. The effects of process parameters on the melt pool are quantitatively discussed by numerical analysis. Furthermore, it has been observed that the surface tension temperature coefficient, Marangoni convection, which is sensitive to the active elements in the titanium alloy composition, also affect the pattern of the fluid flow in the molten pool.

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23

Mo, Dong Ming. "Stability Analysis of Thermocapillary Convection of B₂O₃/Sapphire Melt in an Annular Pool." Materials Science Forum 1036 (June 29, 2021): 175–84. http://dx.doi.org/10.4028/www.scientific.net/msf.1036.175.

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Aiming at the thermocapillary convection stability of sapphire crystal grown by liquid-encapsulated Czochralski method, by non-linear numerical simulation, obtained the flow function and temperature distribution of R-Z cross section, as well as the velocity and temperature distribution at liquid-liquid interface and monitoring point of B2O3/sapphire melt in annular two liquid system, covered with solid upper wall and in microgravity. By means of linear stability analysis, obtained the neutral stability curve and critical stability parameters of the system, and revealed the temperature fluctuation of the liquid-liquid interface. The calculated results of B2O3/sapphire melt were compared with 5cSt silicone oil/HT-70. The results show that under the same geometrical conditions, the flow of B2O3/sapphire melt system is more unstable than 5cSt silicone oil/HT-70, there are two unstable flow patterns, radial three-dimensional steady flow cell and hydrothermal waves near the hot wall. The larger the ratio of Pr number of upper and lower fluid layers is, the better the effect of restraining the flow of lower fluid layers is.

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Giri, Asis, Aram Karbojian, and Bal Raj Sehgal. "ICONE11-36309 Lower Head Failure under coupled Melt Pool Convection and Creep for an American Steel Vessel." Proceedings of the International Conference on Nuclear Engineering (ICONE) 2003 (2003): 68. http://dx.doi.org/10.1299/jsmeicone.2003.68.

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Patel, Sushil, Pradeep Reddy, and Arvind Kumar. "A methodology to integrate melt pool convection with rapid solidification and undercooling kinetics in laser spot welding." International Journal of Heat and Mass Transfer 164 (January 2021): 120575. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2020.120575.

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Tran, Chi-Thanh, and Pavel Kudinov. "The Effective Convectivity Model for Simulation of Molten Metal Layer Heat Transfer in a Boiling Water Reactor Lower Head." Science and Technology of Nuclear Installations 2013 (2013): 1–14. http://dx.doi.org/10.1155/2013/231501.

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This paper is concerned with the development of approaches for assessment of core debris heat transfer and Control Rod Guide Tube (CRGT) cooling effectiveness in case of a Boiling Water Reactor (BWR) severe accident. We consider a hypothetical scenario with stratified (metal layer atop) melt pool in the lower plenum. Effective Convectivity Model (ECM) and Phase-Change ECM (PECM) are developed for the modeling of molten metal layer heat transfer. The PECM model takes into account reduced convection heat transfer in mushy zone and compositional convection that enables simulations of noneutectic binary mixture solidification and melting. The ECM and PECM are (i) validated against relevant experiments for both eutectic and noneutectic mixtures and (ii) benchmarked against CFD-generated data including the local heat transfer characteristics. The PECM is then applied to the analysis of heat transfer in a stratified heterogeneous debris pool taking into account CRGT cooling. The PECM simulation results show apparent efficacy of the CRGT cooling which can be utilized as Severe Accident Management (SAM) measure to protect the vessel wall from focusing effect caused by metallic layer.

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Le, Trong-Nhan, and Yu-Lung Lo. "Effects of sulfur concentration and Marangoni convection on melt-pool formation in transition mode of selective laser melting process." Materials & Design 179 (October 2019): 107866. http://dx.doi.org/10.1016/j.matdes.2019.107866.

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Hekmatjou, Hamidreza, Zhi Zeng, Jiajia Shen, J. P. Oliveira, and Homam Naffakh-Moosavy. "A Comparative Study of Analytical Rosenthal, Finite Element, and Experimental Approaches in Laser Welding of AA5456 Alloy." Metals 10, no. 4 (March 27, 2020): 436. http://dx.doi.org/10.3390/met10040436.

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The thermal regime and microstructural phenomenon are studied by using finite-element (FE) modelling and the analytical Rosenthal equation during laser welding of aluminum alloy 5456 (AA5456) components. A major goal is to determine the merits and demerits of this analytical equation which can be an alternative to FE analysis, and to evaluate the effect of imperative assumptions on predicted consequences. Using results from the analytical and numerical approaches in conjunction with experiments, different physical features are compared. In this study, the results obtained from experiments in terms of melt pool shapes are compared with the predicted ones achieved from the numerical and analytical approaches in which the FE model is more accurate than the Rosenthal equation in the estimation of the melt pool dimensions. Furthermore, as to the partially melted zones, the estimations achieved from the numerical modeling are more genuine than ones from the analytical equation with regards to the experimental results. At high energy density, near keyhole welding mode, the reported results show that experimental melt widths are supposed to be narrower than the fusion widths estimated by the analytical solution. The primary explanation could be the influence of thermal losses that occurred during convection and radiation, which are neglected in the Rosenthal equation. Additionally, the primary dendrite arm spacing (PDAS) estimated with the numerical modeling and the analytical Rosenthal solution is comparable with the experimental results obtained.

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Billotte, Thomas, Dominique Daloz, Bernard Rouat, Guillaume Tirand, Jacob Kennedy, Vincent Robin, and Julien Zollinger. "Microsegregation Model Including Convection and Tip Undercooling: Application to Directional Solidification and Welding." Materials 11, no. 7 (July 20, 2018): 1252. http://dx.doi.org/10.3390/ma11071252.

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The microsegregation behavior of alloy filler metal 52 (FM 52) was studied using microprobe analysis on two different solidification processes. First, microsegregation was characterized in samples manufactured by directional solidification, and then by gas tungsten arc welding (GTAW). The experimental results were compared with Thermo-Calc calculations to verify their accuracy. It was confirmed that the thermodynamic database predicts most alloying elements well. Once this data had been determined, several tip undercooling calculations were carried out for different solidification conditions in terms of fluid flow and thermal gradient values. These calculations allowed the authors to develop a parametrization card for the constants of the microsegregation model, according to the process parameters (e.g., convection in melt pool, thermal gradient, and growth velocity). A new model of microsegregation, including convection and tip undercooling, is also proposed. The Tong–Beckermann microsegregation model was used individually and coupled with a modified Kurz-Giovanola-Trivedi (KGT) tip undercooling model, in order to take into account the convection in the fluid flow at the dendrite tip. Model predictions were compared to experimental results and showed the microsegregation evolution accurately.

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Zitouni, Abdel Halim, Pierre Spiteri, Mouloud Aissani, and Younes Benkheda. "Heat Transfer Mode and Effect of Fluid Flow on the Morphology of the Weld Pool." Defect and Diffusion Forum 406 (January 2021): 66–77. http://dx.doi.org/10.4028/www.scientific.net/ddf.406.66.

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In this work, the heat transfer by conduction and convection mode and effect of fluid flow on the morphology of the weld pool and the welding properties is investigated during Tungsten Inert Gas (TIG) process. In the first part, a computation code under Fortran was elaborated to solve the equations resulting from the finite difference discretization of the heat equation, taking into account the liquid-solid phase change with the associated boundary conditions. In order to calculate the velocity field during welding, the Navier-Stokes equations in the melt zone were simplified and solved considering their stream-vorticity formulation. A mathematical model was developed to study the effect of the melted liquid movement on the weld pool. The evolution of the fraction volume of the liquid and the thermal fields promoted the determination of the molten zone (MZ) and the Heat Affected Zone (HAT) dimensions, which seems to be in good agreement with literature.

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Zitouni, Abdel Halim, Pierre Spiteri, Mouloud Aissani, and Younes Benkheda. "Heat Transfer Mode and Effect of Fluid Flow on the Morphology of the Weld Pool." Defect and Diffusion Forum 406 (January 2021): 66–77. http://dx.doi.org/10.4028/www.scientific.net/ddf.406.66.

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In this work, the heat transfer by conduction and convection mode and effect of fluid flow on the morphology of the weld pool and the welding properties is investigated during Tungsten Inert Gas (TIG) process. In the first part, a computation code under Fortran was elaborated to solve the equations resulting from the finite difference discretization of the heat equation, taking into account the liquid-solid phase change with the associated boundary conditions. In order to calculate the velocity field during welding, the Navier-Stokes equations in the melt zone were simplified and solved considering their stream-vorticity formulation. A mathematical model was developed to study the effect of the melted liquid movement on the weld pool. The evolution of the fraction volume of the liquid and the thermal fields promoted the determination of the molten zone (MZ) and the Heat Affected Zone (HAT) dimensions, which seems to be in good agreement with literature.

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32

Wei, Hongyang, and Yi-Tung Chen. "Numerical investigation of the internally heated melt pool natural convection behavior with the consideration of different high internal Rayleigh numbers." Annals of Nuclear Energy 143 (August 2020): 107427. http://dx.doi.org/10.1016/j.anucene.2020.107427.

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Barua, Shyam, Frank Liou, Joseph Newkirk, and Todd Sparks. "Vision-based defect detection in laser metal deposition process." Rapid Prototyping Journal 20, no. 1 (January 14, 2014): 77–85. http://dx.doi.org/10.1108/rpj-04-2012-0036.

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Purpose – Laser metal deposition (LMD) is a type of additive manufacturing process in which the laser is used to create a melt pool on a substrate to which metal powder is added. The powder is melted within the melt pool and solidified to form a deposited track. These deposited tracks may contain porosities or cracks which affect the functionality of the part. When these defects go undetected, they may cause failure of the part or below par performance in their applications. An on demand vision system is required to detect defects in the track as and when they are formed. This is especially crucial in LMD applications as the part being repaired is typically expensive. Using a defect detection system, it is possible to complete the LMD process in one run, thus minimizing cost. The purpose of this paper is to summarize the research on a low-cost vision system to study the deposition process and detect any thermal abnormalities which might signify the presence of a defect. Design/methodology/approach – During the LMD process, the track of deposited material behind the laser is incandescent due to heating by the laser; also, there is radiant heat distribution and flow on the surfaces of the track. An SLR camera is used to obtain images of the deposited track behind the melt pool. Using calibrated RGB values and radiant surface temperature, it is possible to approximate the temperature of each pixel in the image. The deposited track loses heat gradually through conduction, convection and radiation. A defect-free deposit should show a gradual decrease in temperature which enables the authors to obtain a reference cooling curve using standard deposition parameters. A defect, such as a crack or porosity, leads to an increase in temperature around the defective region due to interruption of heat flow. This leads to deviation from the reference cooling curve which alerts the authors to the presence of a defect. Findings – The temperature gradient was obtained across the deposited track during LMD. Linear least squares curve fitting was performed and residual values were calculated between experimental temperature values and line of best fit. Porosity defects and cracks were simulated on the substrate during LMD and irregularities in the temperature gradients were used to develop a defect detection model. Originality/value – Previous approaches to defect detection in LMD typically concentrate on the melt pool temperature and dimensions. Due to the dynamic and violent nature of the melt pool, consistent and reliable defect detection is difficult. An alternative method of defect detection is discussed which does not involve the melt pool and therefore presents a novel method of detecting a defect in LMD.

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Li, Kai, Zhenyu Zhao, Houming Zhou, Hao Zhou, Jie Yin, Wei Zhang, and Guiyao Zhou. "Numerical Simulation of Effect of Different Initial Morphologies on Melt Hydrodynamics in Laser Polishing of Ti6Al4V." Micromachines 12, no. 5 (May 20, 2021): 581. http://dx.doi.org/10.3390/mi12050581.

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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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Chakraborty, Nilanjan, and Suman Chakraborty. "Distinct influences of turbulence in momentum, heat and mass transfers during melt pool convection in a typical laser surface alloying process." European Physical Journal Applied Physics 36, no. 1 (September 5, 2006): 71–89. http://dx.doi.org/10.1051/epjap:2006098.

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Wang, Xiang Jie, Jian Zhong Cui, and Qing Feng Zhu. "Effects of Low Frequency Electromagnetic Field on the Solidification Structure of 6063 Aluminum Alloy during Hot-Top Casting." Materials Science Forum 675-677 (February 2011): 857–60. http://dx.doi.org/10.4028/www.scientific.net/msf.675-677.857.

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Low frequency electromagnetic (LFE) field was applied during the conventional hot-top casting process. Thermocouples were used to measure the cooling curves from the border to the center of the ingot during steady-state of casting process, cooling curves were obtained, and effects of low frequency electromagnetic field on the solidification, macrostructure during the conventional hot-top casting for 6063 aluminum alloy process were analyzed. The experimental results show that the forced convection caused by the low frequency electromagnetic (LFE) filed can make the melt temperature uniform, promote the evacuation of superheat, make the temperature in the liquid pool lower than the liquidus temperature of 6063 aluminum alloy, increase the number of floating nuclei, make the ingot with fine and homogeneous macrostructure, though there is no addition of any grain refiners.

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Moallemi, M. K., and R. Viskanta. "Experiments on fluid flow induced by melting around a migrating heat source." Journal of Fluid Mechanics 157 (August 1985): 35–51. http://dx.doi.org/10.1017/s0022112085002294.

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A series of melting experiments with a moving horizontal cylindrical heat source at constant surface heat flux have been performed. The heat source was designed in such a way that it could descend under its weight while melting the phase-change material (n-octadecane) surrounding it. The heat-source velocity was measured and the motion and shape of the solid–liquid interface were determined photographically. The effects of the surface heat flux, the density and initial position of the heat source, and the initial subcooling of the solid were investigated and are discussed. Conduction was found to be the dominant heat-transfer mechanism around the lower stagnation point and controlled the terminal velocity of the source. The fluid motion in the melt pool above the heat source was mainly induced by the descent of the source, while natural convection played only a relatively minor role in the motion.

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Chan, C. L., M. M. Chen, and J. Mazumder. "Asymptotic Solution for Thermocapillary Flow at High and Low Prandtl Numbers Due to Concentrated Surface Heating." Journal of Heat Transfer 110, no. 1 (February 1, 1988): 140–46. http://dx.doi.org/10.1115/1.3250444.

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Thermocapillary convection due to nonuniform surface heating is the dominant form of fluid motion in many materials processing operations. The velocity and temperature distributions for the region adjacent to the area of peak surface heating are analyzed for the limiting cases of large and small Prandtl numbers. For a melt pool whose depth and width are large relative to the thermal and viscous boundary layers, it is shown that the most important parameter is the curvature (i.e., ∇2q) of the surface heat flux distribution. The solutions of the temperature and stream functions are presented, some of which are in closed form. Simple, explicit expressions for the velocity and maximum temperature are presented. These results are found to be quite accurate for realistic Prandtl number ranges, in comparison with exact solutions for finite Prandtl numbers. Besides being more concise than exact results, the asymptotic results also display the Prandtl number dependence more clearly in the respective ranges.

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Fyrillas, Ioannou, Papadakis, Rebholz, and Doumanidis. "Phase Change with Density Variation and Cylindrical Symmetry: Application to Selective Laser Melting." Journal of Manufacturing and Materials Processing 3, no. 3 (July 25, 2019): 62. http://dx.doi.org/10.3390/jmmp3030062.

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In this paper we introduce an analytical approach for predicting the melting radius during powder melting in selective laser melting (SLM) with minimum computation duration. The purpose of this work is to evaluate the suggested analytical expression in determining the melt pool geometry for SLM processes, by considering heat transfer and phase change effects with density variation and cylindrical symmetry. This allows for rendering first findings of the melt pool numerical prediction during SLM using a quasi-real-time calculation, which will contribute significantly in the process design and control, especially when applying novel powders. We consider the heat transfer problem associated with a heat source of power Q' (W/m) per unit length, activated along the span of a semi-infinite fusible material. As soon as the line heat source is activated, melting commences along the line of the heat source and propagates cylindrically outwards. The temperature field is also cylindrically symmetric. At small times (i.e., neglecting gravity and Marangoni effects), when the density of the solid material is less than that of the molten material (i.e., in the case of metallic powders), an annulus is created of which the outer interface separates the molten material from the solid. In this work we include the effect of convection on the melting process, which is shown to be relatively important. We also justify that the assumption of constant but different properties between the two material phases (liquid and solid) does not introduce significant errors in the calculations. A more important result; however, is that, if we assume constant energy input per unit length, there is an optimum power of the heat source that would result to a maximum amount of molten material when the heat source is deactivated. The model described above can be suitably applied in the case of selective laser melting (SLM) when one considers the heat energy transferred to the metallic powder bed during scanning. Using a characteristic time and length for the process, we can model the energy transfer by the laser as a heat source per unit length. The model was applied in a set of five experimental data, and it was demonstrated that it has the potential to quantitatively describe the SLM process.

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Huang, Xu, Chang Liu, Hao Zhang, Changrong Chen, Guofu Lian, Jibin Jiang, Meiyan Feng, and Mengning Zhou. "Microstructure Control and Friction Behavior Prediction of Laser Cladding Ni35A+TiC Composite Coatings." Coatings 10, no. 8 (August 9, 2020): 774. http://dx.doi.org/10.3390/coatings10080774.

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The premise of surface strengthening and repair of high valued components is to identify the relationship between coating formulation, structure, and properties. Based on the full factorial design, the effects of process parameters (laser power, scanning speed, gas-powder flow rate, and weight fraction of TiC) on the phase composition, microstructure, and element distribution of Ni35A/TiC cladding layer were investigated, followed by the cause identification of wear behavior. Through ANOVA, the correlation was established with good prediction accuracy (R2 = 0.9719). The most important factors affecting the wear rate of the cladding layer were recognized as laser power and particle ratio with a p-value < 0.001. The cladding layer was mainly comprised of Ni3Fe and TiC0.957. The excessive laser power would enhance the process of convection-diffusion of the melt pool, increase dilution, and improve wear volume. High laser power facilitates renucleation and growth of the hard phase, especially the complete growth of secondary axis dendrite for the top region. Increased TiC significantly changes the microstructure of the hard phase into a non-direction preferable structure, which prevents stress concentration at tips and further improves the mechanical properties. The research results are a valuable support for the manipulation of microstructure and prediction of wear behavior of composite cladding layer.

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Chiang, Ming-Feng, Tzu-Yuan Lo, Ping-Hui Chien, Chih-Hsien Chi, Kai-Chun Chang, An-Chou Yeh, and Ren-Kae Shiue. "The Dilution Effect in High-Power Disk Laser Welding the Steel Plate Using a Nickel-Based Filler Wire." Metals 11, no. 6 (May 27, 2021): 874. http://dx.doi.org/10.3390/met11060874.

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High-power disk laser welding a steel plate using the Inconel 82 (IN82) filler wire with a 1.2 and 3.0 m/min feeding rate has been investigated in the experiment. The rapid thermal cycle combined with convection induced by the keyhole mechanism in laser welding results in the rapid solidification of the fusion zone (FZ). However, the microstructure of the FZ is not homogeneous at the macroscopic scale. The dilution of the FZ is important in determining the final microstructure of the weldment. For the specimen with a 1.2 m/min wire feeding rate, a lower amount of Ni-based IN82 filler is introduced into the weld pool, and the dilution of the FZ is between 65% and 100%. The BCC structure with high density boundaries dominates the entire FZ. For the specimen with a 3.0 m/min wire feeding rate, part of the filler melt is trapped on the top of the weld pool, and solidified into austenite alloyed with a Ni concentration above 15 at%. The range of dilution in the FZ with a 3.0 m/min wire feeding rate is decreased to 50–90%. There are hot cracks initiated/propagated along interdendritic austenite and in the austenite free of boundaries. Boundaries, especially for high-angle ones, in the BCC structure retard hot crack propagation in the FZ. The application of quantitative chemical analyses of Fe or Ni concentrations in the weldment provides a good approximation in evaluating the dilution of the FZ in laser welding. The methodology proposed in this study shows potential to obtain the dilution of any specific location in the FZ for industrial application in the future.

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Guan, Jieren, Xiaowei Zhang, Yehua Jiang, and Yongnian Yan. "Insights into fabrication mechanism of pure copper thin wall components by selective infrared laser melting." Rapid Prototyping Journal 25, no. 8 (September 9, 2019): 1388–97. http://dx.doi.org/10.1108/rpj-06-2018-0143.

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Purpose This study aims to obtain the mechanistic insights for the fabrication of pure copper thin wall components by selective infrared (IR) laser melting (SLM) and correlated with microstructure development, microhardness, surface morphology and phase analysis. Experimental processes for single track and selection of substrate materials have been studied using a combination of different laser powers and scanning speeds. Design/methodology/approach SLM of pure copper was performed on a YONGNIAN Laser YLMS-120 SLM machine using an Nd: YAG fiber laser operating at 1,060 nm in the NIR region. Single-track experiments and processing parameters are investigated through different combinations of laser power and scanning speed. The microstructure of the fabricated pure copper samples by SLM technique was analyzed by means of X-ray diffraction, scanning electron microscope equipped with energy disperse spectrometer, optical microscope (OM) and micro-hardness tester. Findings Steel-based substrates were found suitable for pure copper manufacturing due to sufficient heat accumulation. The width of a single track was determined by liner energy density, showing discontinuities and irregular morphologies at low laser powers and high scanning speeds. As a result of instability of the molten pool induced by Marangoni convection, cracks and cavities were observed to appear along grain boundaries in the microstructure. The top surface morphology of SLM-processed component showed a streamflow structure and irregular shapes. However, the powder particles attached to side surface, which manifest copper powders, are even more sensitive to melt pool of contour track. The crystal phase characteristics of copper components indicated increasing crystallite size of a-Cu, and the decreasing intensity of diffraction peak was attributed to the presence of defects during SLM. The maximum relative density and microhardness were 82 per cent and 61.48 HV0.2, respectively. The minimum thickness of a pure copper thin wall component was 0.2 mm. Originality/value This paper demonstrated the forming mechanism and explored feasibility of pure copper thin wall parts by SLM technology in the NIR region. The surface morphology, microstructure and crystal structure were preliminary studied with laser processing parameters.

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Kukharev, A. L. "Selecting the rational electrodes location in a DC multi-electrode arc furnace." Vestnik IGEU, no. 3 (June 30, 2020): 23–31. http://dx.doi.org/10.17588/2072-2672.2020.3.023-031.

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One of the main design parameters of multi-electrode furnaces, which largely determines their heat and eco-nomic indicators, is the ratio of the pitch circle diameter of electrodes to the bath diameter Dp/Db. The existing methods for choosing rational design parameters are more relevant to arc furnaces operating on alternating current of industrial frequency. For multi-electrode direct current furnaces, which use magnetohydrodynamic effects to improve mixing conditions and temperature homogenization of the melt, there is no relationship between the heat transfer parameters and the pitch circle diameter of electrodes. This work is a continuation of a number of patents and articles. Elsewhere, the design was justified, a mathematical model of magnetohydrodynamic and thermal processes in the melt of the furnace containing three roof arc and three bottom electrodes was developed, the model was verified through the results of physical experiments, and the parameters of heat transfer in the furnace at Dp/Db ≈ 0,2 were studied. The proposed type of furnace requires the study of the Dp/Db effect on the heat transfer parameters in the melt, which will allow a rational choice of the design parameter. The results were obtained using a three-dimensional mathematical model of magnetohydrodynamic and thermal processes in the steel melt constructed with the non-induction approximation and taking into account the k- turbulence model. The results were processed using methods of analysis of vortex structures and estimation of the integral parameters of hydrodynamic and thermal processes in the molten bath. Numerical experiments have been carried out with the design parameter Dp/Db varying from 0,2 to 0,5. New scientific data on the patterns of changes in the structure of flows and heat transfer parameters in the molten pool of a six-electrode furnace have been obtained. Dp/Db increase within the indicated range causes the increase of intensity of vertical vortex flows circulating between the axis of the corresponding electric arc and the axis of the bath and of the azimuthal flows circulating in horizontal sections of the bath. Vortex flows formed due to natural convection near the side walls of the furnace are suppressed. The maximum value zones of the effective thermal conductivity that reaches 1,8·105 W/(m·K) are redistributed to the central part of the bath, which contributes to increasing temperature distribution efficiency in the bath. The obtained results allow recommending a rational range of values of Dp/Db within 0,4–0,5, which decreases the volume of stagnant zones in the proposed six-electrode furnace by more than 40 % and increases the integral values of the Nusselt number over the depth of the horizontal section of the bath on average by more than 10 %. The obtained data revealing the possibility of improving the mixing conditions and increasing the heat transfer efficiency in the melt of the six-electrode furnace can be recommended for choosing the Dp/Db ratio when designing high power furnace.

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Ross, Ingo, André Temmler, Moritz Küpper, Stephan Prünte, Marco Teller, Jochen M. Schneider, and Reinhart Poprawe. "Laser Polishing of Cold Work Steel AISI D2 for Dry Metal Forming Tools: Surface Homogenization, Refinement and Preparation for Self-Assembled Monolayers." Key Engineering Materials 767 (April 2018): 69–76. http://dx.doi.org/10.4028/www.scientific.net/kem.767.69.

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Liquid lubrication guarantees high precision and surface quality of workpieces in industrial forming processes. In the case of aluminum cold extrusion, wear and cold welding due to direct contact of tool and workpiece are usually prevented by the extensive use of lubricants. Since the use of lubricants is economically and ecologically unfavorable, surface treatments of tools by, e.g. laser polishing and/or coatings are in the focus of current investigations to substitute these lubricants and establish so called “dry metal forming” processes. The material AISI D2, a ledeburitic 12% chromium steel which is known to have a significant amount of chromium carbide precipitations, is widely used in cold extrusion for forming tools. The large fraction of chromium carbide precipitations, however, hinder the formation of a dense self-assembled monolayer (SAM) that is necessary to avoid direct contact of reactive aluminum with surface oxides of the tool. Therefore, a homogeneous distribution of the chemical elements with a smaller fraction or no chromium carbides in the steel matrix, particularly in the tool surface, is aimed for. Using laser polishing, the surface layer is molten by continuous or pulsed laser radiation. Within the melt pool, the elementary distribution is homogenized as a result of thermal convection and diffusion processes, as well as a smoothed surface and a grain refinement are achieved. Consequently, the effects of the surface treatment by laser polishing on the area coverage of self-assembled monolayers are investigated. Thus, a combined surface treatment by laser polishing and functionalization with a dense self-assembled monolayer shall reduce overall adhesive wear. For this investigation, several specimens of conventional manufactured and powder metallurgical molten AISI D2 are laser polished using continuous or pulsed laser radiation or a combination of both. The resulting surfaces are investigated by microscopy and spectroscopic techniques to analyze the surface topography and the elemental distribution near to the surface. These results are compared to those of conventionally hand-polished specimens. Furthermore, the influence of the element homogenization and grain refinement on the area coverage of self-assembled monolayers is explored. First results show that laser polishing of AISI D2 is suitable to achieve a reduction of grain size and a more homogeneous distribution of chromium carbides within the surface layer.

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Shi, Wanyuan, Guoyuan Li, Xi Liu, You-Rong Li, Lan Peng, and Nobuyuki Imaishi. "Thermocapillary Convection and Buoyant-Thermocapillary Convection in the Annular Pools of Silicon Melt and Silicone Oil." Journal of Superconductivity and Novel Magnetism 23, no. 6 (January 23, 2010): 1169–72. http://dx.doi.org/10.1007/s10948-010-0662-7.

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Luo, Simin, Yapei Zhang, Dalin Zhang, Guanghui Su, and Suizheng Qiu. "SIMULATIONS ON NATURAL CONVECTION OF STRATIFIED MELT POOLS WITH VOLUMETRIC HEAT GENERATION." Proceedings of the International Conference on Nuclear Engineering (ICONE) 2019.27 (2019): 1948. http://dx.doi.org/10.1299/jsmeicone.2019.27.1948.

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Seigel, Robert B., and Susan C. van den Heever. "Squall-Line Intensification via Hydrometeor Recirculation." Journal of the Atmospheric Sciences 70, no. 7 (July 1, 2013): 2012–31. http://dx.doi.org/10.1175/jas-d-12-0266.1.

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Abstract Many studies have demonstrated the intimate connection between microphysics and deep moist convection, especially for squall lines via cold pool pathways. The present study examines four numerically simulated idealized squall lines using the Regional Atmospheric Modeling System (RAMS) and includes a control simulation that uses full two-moment microphysics and three sensitivity experiments that vary the mean diameter of the hail hydrometeor size distribution. Results suggest that a circulation centered at the freezing level supports midlevel convective updraft invigoration through increased latent heating. The circulation begins with hail hydrometeors that initiate within the convective updraft above the freezing level and are then ejected upshear because of the front-to-rear flow of the squall line. As the hail falls below the freezing level, the rear-inflow jet (RIJ) advects the hail hydrometeors downshear and into the upshear flank of the midlevel convective updraft. Because the advection occurs below the freezing level, some of the hail melts and sheds raindrops. The addition of hail and rain to the updraft increases latent heating owing to both an enhancement in riming and vapor deposition onto hail and rain. The increase in latent heating enhances buoyancy within the updraft, which leads to an increase in precipitation and cold pool intensity that promote a positive feedback on squall-line strength. The upshear-tilted simulated squall lines in this study indicate that as hail size is decreased, squall lines are invigorated through the recirculation mechanism.

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Kim, Su-Hyeon, Hae-Kyun Park, and Bum-Jin Chung. "Natural convection of the oxide pool in a three-layer configuration of core melts." Nuclear Engineering and Design 317 (June 2017): 100–109. http://dx.doi.org/10.1016/j.nucengdes.2017.03.036.

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Kao, A., T. Gan, C. Tonry, I. Krastins, and K. Pericleous. "Thermoelectric magnetohydrodynamic control of melt pool dynamics and microstructure evolution in additive manufacturing." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 378, no. 2171 (April 13, 2020): 20190249. http://dx.doi.org/10.1098/rsta.2019.0249.

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Large thermal gradients in the melt pool from rapid heating followed by rapid cooling in metal additive manufacturing generate large thermoelectric currents. Applying an external magnetic field to the process introduces fluid flow through thermoelectric magnetohydrodynamics. Convective transport of heat and mass can then modify the melt pool dynamics and alter microstructural evolution. As a novel technique, this shows great promise in controlling the process to improve quality and mitigate defect formation. However, there is very little knowledge within the scientific community on the fundamental principles of this physical phenomenon to support practical implementation. To address this multi-physics problem that couples the key phenomena of melting/solidification, electromagnetism, hydrodynamics, heat and mass transport, the lattice Boltzmann method for fluid dynamics was combined with a purpose-built code addressing solidification modelling and electromagnetics. The theoretical study presented here investigates the hydrodynamic mechanisms introduced by the magnetic field. The resulting steady-state solutions of modified melt pool shapes and thermal fields are then used to predict the microstructure evolution using a cellular automata-based grain growth model. The results clearly demonstrate that the hydrodynamic mechanisms and, therefore, microstructure characteristics are strongly dependent on magnetic field orientation. This article is part of the theme issue ‘Patterns in soft and biological matters'.

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Saedi, Hamid Reza, and William Unkel. "Thermal-Fluid Model for Weld Pool Geometry Dynamics." Journal of Dynamic Systems, Measurement, and Control 111, no. 2 (June 1, 1989): 268–76. http://dx.doi.org/10.1115/1.3153046.

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This paper describes an experimental and analytical program to provide a predictive weld pool modeling technique useful as one component of a feed back control automatic welding machine. Stationary arc experiments were performed with stainless-steel plugs and showed two different regimes in the growth of the weld pool. Initially the surface tension driven flow was dominant in the shaping of the pool (t<3 s). Once enough material was molten, the electromagnetic (E-M) forces became the dominant factor. This behavior was also observed for the moving arc cases. Detailed measurements of the pool shape were made for steady and transient conditions. A thermal-fluid model of the weld pool was developed for the case of a stationary arc in which a deep paraboloidal pool is formed. This model uses the current and heat distribution at the anode surface as inputs. Matching of convective and conductive heat fluxes along the melt boundary was used to predict the weld pool shape. The conductive heat flux on the solid side was calculated by the finite element method. The convective heat flux on the liquid side was calculated by solving the fluid and heat transfer equations assuming a single cell circulation flow inside the weld pool. For the stationary arc cases under consideration, the E-M force field was found to dominate the flow pattern. This method was capable of determining the transient in weld pool geometry for changes in different process conditions, e.g., arc length, pulsed current. Comparison between experiments and the model showed agreement of weld pool size (top width and penetration) within 10 percent. This modeling technique can be extended to analyse weld pools with multi-cell circulation patterns which are encountered in the moving arc and the stationary arc cases with a shallow pool.

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Journal articles on the topic 'Melt pool convection'

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