Laser Powder Bed Fusion (LPBF) of In718 and the Impact of Pre-Heating at 500 and 1000 °C: Operando Study

Rehman, Asif Ur; Pıtır, Fatih; Salamcı, Metin U.

doi:10.3390/ma14216683

Cited by 15 publications

(6 citation statements)

References 94 publications

(127 reference statements)

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“…h is the convection coefficient, and ϵ is the emissivity. Some analytical models neglect these boundary contributions in AM processes, such as the well-known simple Rosenthal approach [44], even if their effect is important on the temperature of the clad. The difficulty of measuring the convection coefficient that evolves with the geometry explains why this coefficient is often assumed constant, or just with piecewise constant values [45].…”

Section: Methodsmentioning

confidence: 99%

Impact of Boundary Parameters Accuracy on Modeling of Directed Energy Deposition Thermal Field

Gallo,

Duchêne,

Quy Duc Pham

et al. 2024

Metals

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Within the large Additive Manufacturing (AM) process family, Directed Energy Deposition (DED) can be used to create low-cost prototypes and coatings, or to repair cracks. In the case of M4 HSS (High Speed Steel), a reliable computed temperature field during DED process allows the optimization of the substrate preheating temperature value and other process parameters. Such optimization is required to avoid failure during the process, as well as high residual stresses. If 3D DED simulations provide accurate thermal fields, they also induce huge computation time, which motivates simplifications. This article uses a 2D Finite Element (FE) model that decreases the computation cost through dividing the CPU time by around 100 in our studied case, but it needs some calibrations. As described, the identification of a correct data set solely based on local temperature measurements can lead to various sets of parameters with variations of up to 100%. In this study, the melt pool depth was used as an additional experimental measurement to identify the input data set, and a sensitivity analysis was conducted to estimate the impact of each identified parameter on the cooling rate and the melt pool dimension.

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Section: Methodsmentioning

confidence: 99%

Impact of Boundary Parameters Accuracy on Modeling of Directed Energy Deposition Thermal Field

Gallo,

Duchêne,

Quy Duc Pham

et al. 2024

Metals

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“…Equations ( 16)-( 18) have been taken from Refs. [58,62,63]. The curvature and the normal vector can be obtained via the subscript n in the exposed liquid:…”

Section: Motion Equationsmentioning

confidence: 99%

Laser Melting Deposition Additive Manufacturing of Ti6Al4V Biomedical Alloy: Mesoscopic In-Situ Flow Field Mapping via Computational Fluid Dynamics and Analytical Modelling with Empirical Testing

Mahmood

Rehman

Pıtır³

et al. 2021

Materials

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Laser melting deposition (LMD) has recently gained attention from the industrial sectors due to producing near-net-shape parts and repairing worn-out components. However, LMD remained unexplored concerning the melt pool dynamics and fluid flow analysis. In this study, computational fluid dynamics (CFD) and analytical models have been developed. The concepts of the volume of fluid and discrete element modeling were used for computational fluid dynamics (CFD) simulations. Furthermore, a simplified mathematical model was devised for single-layer deposition with a laser beam attenuation ratio inherent to the LMD process. Both models were validated with the experimental results of Ti6Al4V alloy single track depositions on Ti6Al4V substrate. A close correlation has been found between experiments and modelling with a few deviations. In addition, a mechanism for tracking the melt flow and involved forces was devised. It was simulated that the LMD involves conduction-mode melt flow only due to the coaxial addition of powder particles. In front of the laser beam, the melt pool showed a clockwise vortex, while at the back of the laser spot location, it adopted an anti-clockwise vortex. During printing, a few partially melted particles tried to enter into the molten pool, causing splashing within the melt material. The melting regime, mushy area (solid + liquid mixture) and solidified region were determined after layer deposition. This research gives an in-depth insight into the melt flow dynamics in the context of LMD printing.

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“…Additive manufacturing (AM) has revolutionized many industries (Furferi and Rehman, 2023), including construction (Ur Rehman and Sglavo, 2020, 2022), biomedical (Mahmood, 2022), aerospace and biomedical to achieve design flexibility and shortened time to market (Mushtaq et al , 2022; Rehman et al , 2021a, 2021b). Laser powder bed fusion (L-PBF) is an AM process for making parts and freeform objects in which the production layer is selectively consolidated by a high-energy laser beam following powder deposition (Zhang et al , 2014; Song et al , 2012).…”

Section: Introductionmentioning

confidence: 99%

Understanding the consolidation mechanism of selective laser sintering/powder bed selective laser process of ceramics: Hydroxyapatite case

Ur Rehman,

Navarrete-Segado,

Salamci

et al. 2024

RPJ

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Purpose The consolidation process and morphology evolution in ceramics-based additive manufacturing (AM) are still not well-understood. As a way to better understand the ceramic selective laser sintering (SLS), a dynamic three-dimensional computational model was developed to forecast thermal behavior of hydroxyapatite (HA) bioceramic. Design/methodology/approach AM has revolutionized automotive, biomedical and aerospace industries, among many others. AM provides design and geometric freedom, rapid product customization and manufacturing flexibility through its layer-by-layer technique. However, a very limited number of materials are printable because of rapid melting and solidification hysteresis. Melting-solidification dynamics in powder bed fusion are usually correlated with welding, often ignoring the intrinsic properties of the laser irradiation; unsurprisingly, the printable materials are mostly the well-known weldable materials. Findings The consolidation mechanism of HA was identified during its processing in a ceramic SLS device, then the effect of the laser energy density was studied to see how it affects the processing window. Premature sintering and sintering regimes were revealed and elaborated in detail. The full consolidation beyond sintering was also revealed along with its interaction to baseplate. Originality/value These findings provide important insight into the consolidation mechanism of HA ceramics, which will be the cornerstone for extending the range of materials in laser powder bed fusion of ceramics.

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Laser Powder Bed Fusion (LPBF) of In718 and the Impact of Pre-Heating at 500 and 1000 °C: Operando Study

Cited by 15 publications

References 94 publications

Impact of Boundary Parameters Accuracy on Modeling of Directed Energy Deposition Thermal Field

Impact of Boundary Parameters Accuracy on Modeling of Directed Energy Deposition Thermal Field

Laser Melting Deposition Additive Manufacturing of Ti6Al4V Biomedical Alloy: Mesoscopic In-Situ Flow Field Mapping via Computational Fluid Dynamics and Analytical Modelling with Empirical Testing

Understanding the consolidation mechanism of selective laser sintering/powder bed selective laser process of ceramics: Hydroxyapatite case

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