Prediction of melt pool depth and dilution in laser powder deposition

Fathi, Alireza; Toyserkani, Ehsan; Khajepour, Amir; Durali, Mohammad

doi:10.1088/0022-3727/39/12/022

Cited by 140 publications

(58 citation statements)

References 17 publications

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“…To confirm experimental correlations between melt-pool geometries and lateral menisci, an analytical model was developed, with an analytical description for every melt-pool, considering a similar approach than Fathi et al (2006). On a 2D cross section, each melt-pool was considered as the sum of two semi-ellipses x 2 /a 2 + y 2 /b 2 = 1 (one for the upper part, and one for the lower part).…”

Section: Analytical Description Of Surface Finishmentioning

confidence: 99%

“…All these factors influence the thermal history T = f(x, y, z, t) of the part, and contribute not only to the melt-pool shapes, and the resulting layer growth, but also to the final metallurgical and mechanical properties Recently (2006Recently ( -2011, intensive numerical work has been carried out to model the DMD process, starting from the laser-powder interaction, to the thermo-mechanical calculation of residual stresses, including or-not metallurgical aspects. Authors like Fathi et al (2006) proposed rather simplified predictive models to predict the geometrical characteristics of the walls by assuming a solid state during the process. Whereas, more complex thermohydraulic calculations considered free moving surfaces, either on 2D multilayers configurations like Morville et al (2011), or on 3D single layer as shown by Qi et al (2006) or Kumar and Roy (2009).…”

Section: Introductionmentioning

confidence: 99%

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Influence of various process conditions on surface finishes induced by the direct metal deposition laser technique on a Ti–6Al–4V alloy

Gharbi

Peyre

Gorny

et al. 2013

Journal of Materials Processing Technology

143

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is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. a b s t r a c tThe direct metal deposition (DMD) with laser is a free-form metal deposition process for manufacturing dense pieces, which allows generating a prototype or small series of near net-shape structures. One of the most critical issues is that produced pieces have a deleterious surface finish which systematically requires post machining steps. This problem has never been fully addressed before. The present work describes investigations on the DMD process, using an Yb-YAG disk laser, and a widely used titanium alloy (Ti-6Al-4V) to understand the influence of the main process parameters on the surface finish quality. The focus of our work was: (1) to understand the physical mechanisms responsible for deleterious surface finishes, (2) to propose different experimental solutions for improving surface finish.In order to understand the physical mechanisms responsible for deleterious surface finishes, we have carried out: (1) a precise characterization of the laser beam and the powder stream; (2) a large number of multi-layered walls using different process parameters (P(W), V(m/min), D m (g/min), Gaussian or uniform beam distribution); (3) a real time fast camera analysis of melt pool dynamics and melt-pool -powder stream coupling; (4) a characterization of wall morphologies versus process parameters using 2D and 3D profilometry.The results confirm that surface degradation depends on two distinct aspects: the sticking of nonmelted or partially melted particles on the free surfaces, and the formation of menisci with more or less pronounced curvature radii. Among other aspects, a reduction of layer thickness and an increase of melt-pool volumes to favor re-melting processes are shown to have a beneficial effect on roughness parameters. Last, a simple analytical model was proposed to correlate melt-pool geometries to resulting surface finishes.

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Section: Analytical Description Of Surface Finishmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Influence of various process conditions on surface finishes induced by the direct metal deposition laser technique on a Ti–6Al–4V alloy

Gharbi

Peyre

Gorny

et al. 2013

Journal of Materials Processing Technology

143

View full text Add to dashboard Cite

show abstract

“…Various numerical or analytical models have also addressed the formation of wall geometries by considering either element activation including a time discretization of the process, 5,6 predefined analytical function of the final shape like those by Pinkerton and Li 7 or Fathi et al, 8 or a more physical self-consistent displacement of the free surface including the powder feed distribution in the velocity 2,9,10 with the use of a level-set method. However, except in Ref.…”

Section: Introductionmentioning

confidence: 99%

Simplified numerical model for the laser metal deposition additive manufacturing process

Peyre¹,

Dal²,

Pouzet³

et al. 2017

Journal of Laser Applications

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The laser metal deposition (LMD) laser technique is a free-form metal deposition process, which allows generating near net-shape structures through the interaction of a powder stream and a laser beam. A simplified numerical model was carried out to predict layer heights together with temperature distributions induced by the (LMD) process on a titanium alloy, and a metal matrix composite. Compared with previously developed models, this simplified approach uses an arbitrary Lagrangian Eulerian free surface motion directly dependent on the powder mass feed rate Dm. Considering thin wall builds of Ti-6Al-4V titanium alloy, numerical results obtained with comsol 4.3 Multiphysics software were successfully compared with the experimental data such as geometrical properties of manufactured walls, fast camera molten pools measurements, and thermocouple temperature recordings in the substrate during the manufacturing of up to 10 LMD. Even if the model did not consider coupled hydraulic-thermal aspects, it provides a more realistic local geometrical description of additive layer manufacturing walls than simpler thermal models, with much shorter calculation times than more sophisticated approaches considering thermocapillary fluid flow. In a second step, microstructures (equiaxed or columnar) were predicted on Ti-6Al-4V walls using microstructural map available in the literature, and local thermal gradients G (K/m) and solidification rate R (m/s) provided by the FE calculation near the solidification front.

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“…Control of these characteristics requires a good understanding of the relationship between the independent process variables, such as laser power, beam parameters, transverse speed, powder feeding rate shielding gas speed, and the deposit properties such as track geometry, mechanical properties, surface roughness, and microstructure. Several authors have attempted to make the link via analytical [7], numerical or empirical means [8]. However, most of these studies considered the melt pool as quasi-stationary and thus do not consider factors that caused or resulted from pool instability.…”

Section: Introductionmentioning

confidence: 99%

Effects of Melt Pool Variables and Process Parameters in Laser Direct Metal Deposition of Aerospace Alloys

Shah

Pinkerton

Ahmad

et al. 2010

Materials and Manufacturing Processes

114

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Despite considerable advances in of laser direct metal deposition (LDMD) process optimization, there is rather limited work reported on the effects of melt pool variables on the final deposit characteristics. This article considers the effects of process parameters and melt pool characteristics on the deposition of Inconel 718 powder on a Ti-6Al-4V thin wall. A 1.5 kW diode laser and LDMD system is used to produce a series of deposits. Images of the process are captured using Cu-vapor laser illumination and a high speed camera with long range microscopy optics, and quantitative results are extracted via image analysis. Process parameters such as carrier gas flow rate, powder mass flow rate and laser operating mode (CW and pulsed) and in process variables such as quantified melt pool disturbance, and final part characteristics are correlated and discussed. Scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and energy dispersive X-ray spectroscopy (EDS) are used to analyze deposited clads in terms of elemental composition and flow characteristics in the deposition melt pool. Melt pool disturbance is found to be a vital parameter in determining the surface roughness of the final part. An inverse relation between the mean surface disturbance of the melt pool and the surface roughness of the part is observed, and carrier gas flow rate and powder mass flow rate both affect the overall melt pool size. The work has implications for the selection of process parameters for commercial laser deposition processes-the speed with which powder is delivered to the melt pool as well as the mass flow rate may need to be taken into account when calculating build rate and for a good surface finish requiring minimum post process finishing a stable melt pool may actually be the worst situation.

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Prediction of melt pool depth and dilution in laser powder deposition

Cited by 140 publications

References 17 publications

Influence of various process conditions on surface finishes induced by the direct metal deposition laser technique on a Ti–6Al–4V alloy

Influence of various process conditions on surface finishes induced by the direct metal deposition laser technique on a Ti–6Al–4V alloy

Simplified numerical model for the laser metal deposition additive manufacturing process

Effects of Melt Pool Variables and Process Parameters in Laser Direct Metal Deposition of Aerospace Alloys

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