Multiphysics modelling of lack-of-fusion voids formation and evolution in IN718 made by multi-track/multi-layer L-PBF

Bayat, Mohamad; Mohanty, Sankhya; Hattel, Jesper Henri

doi:10.1016/j.ijheatmasstransfer.2019.05.003

Cited by 168 publications

(68 citation statements)

References 55 publications

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“…They show that the surface forces and the density of packed powder bed are responsible for binding faults. Bayat et al [24] show good experimental agreement on melt pool depth estimation when coupling resolution of heat conservation equations with the hydrodynamical solution. Aggarwal et al [25] used a similar approach demonstrating the capability to get the transition from a conduction to a keyhole mode by reducing the laser spot radius with good agreement through experimental work.…”

Section: Introductionmentioning

confidence: 97%

“…For these reasons, many authors developed models at a smaller scale (mesoscopic) to provide better estimations of local thermal gradients and bead shape morphologies. Particle-mesoscale models have been developped, using the discrete element method (DEM), or the FEM, coupled with CFD methods [12,[21][22][23][24][25]. Bidare et al [12] use a multiphysics model including laser plume and finally conclude that the laser plume velocity in LPBF process goes from 300 to 600 m.s 1 (depending on the laser input energy in the Knudsen layer and decreases exponentially with height to a value close to 100 m.s 1 .…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Numerical study of the impact of vaporisation on melt pool dynamics in Laser Powder Bed Fusion - Application to IN718 and Ti–6Al–4V

Queva

Guillemot

Moriconi

et al. 2020

Additive Manufacturing

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A finite element model of Laser Powder Bed Fusion (LPBF) process applied to metallic alloys at a mesoscopic scale is presented. This Level-Set model allows to follow melt pool evolution and track development during building. A volume heat source model is used for laser/powder interaction considering the material absorption coefficients, while a surface heat source is used to consider the high laser energy absorption by dense metal alloys. An energy solver is applied considering convection and conductivity evolution in the system. Shrinkage during consolidation from powder to dense material is modelled by a compressible Newtonian constitutive law. An automatic remeshing strategy is also used to provide a good compromise between accuracy and computing time. Different cases are investigated to demonstrate the influence of the vaporisation phenomena, of material properties and of laser scan strategy on bead morphology.

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Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Numerical study of the impact of vaporisation on melt pool dynamics in Laser Powder Bed Fusion - Application to IN718 and Ti–6Al–4V

Queva

Guillemot

Moriconi

et al. 2020

Additive Manufacturing

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show abstract

“…Therefore, a significant portion of current AM research is focussed on investigating these different aspects of precision, namely the repeatability, predictability, and robustness of the process. Various approaches have been employed for this purpose, including investigating the design for precision AM using topology optimization [11], computational modeling of the L-PBF process [12], and statistical process optimization studies [13]. These methods are also complemented by studies on improving methods for the finishing of parts [14], as well as for metrology [15].…”

Section: Introductionmentioning

confidence: 99%

“…Bayat et al developed a multi-physic numerical model of the L-PBF process, which was then used to track the formation of porosities that cause imprecision while printing. Their results indicate that porosities are largely caused due to the improper fusion of particles between tracks [12]. Charles et al investigated the effects of process parameters on the surface texture of a down-facing part and showed that the interaction and interdependency of process parameters have the greatest effect on the surface roughness as they directly affect the degree of dross formation due to the various levels of energy density applied to the powder [13].…”

Section: Introductionmentioning

confidence: 99%

Dimensional Errors Due to Overhanging Features in Laser Powder Bed Fusion Parts Made of Ti-6Al-4V

et al. 2020

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The rise in popularity of Additive Manufacturing technologies and their increased adoption for manufacturing have created a requirement for their fast development and maturity. However, there is still room for improvement when compared with conventional manufacturing in terms of the predictability, quality, and robustness. Statistical analysis has proven to be an excellent tool for developing process knowledge and optimizing different processes efficiently and effectively. This paper uses a novel method for printing overhanging features in Ti-6Al-4V metal parts, by varying process parameters only within the down-facing area, and establishes a methodology for predicting dimensional errors in flat 45° down-facing surfaces. Using the process parameters laser power, scan speed, scan spacing, scan pattern, and layer thickness, a quadratic regression equation is developed and tested. An Analysis of variance (ANOVA) analysis concluded that, within the down-facing area, the laser power is the most significant process parameter, followed by the layer thickness and scan speed. Comparatively, the scanning pattern is determined to be insignificant, which is explained by the small down-facing area where the various scanning patterns play no role. This paper also discusses the interaction effects between parameters. Some thoughts on the next steps to be taken for further validation are discussed.

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“…The finite element method (FEM) which develops a detailed numerical model that describes the physical aspects of the procedure, is one modelling approach extensively used to provide a good understanding of the process behavior. One drawback of this method is the complexity of the models and the computational power required to investigate a wide range of process parameters, or different combinations of parameter sets, in a parametric study [14]. Statistical analysis is another approach that optimizes process parameters by developing a regression model that defines the relationship between the input parameters and the output variables.…”

Section: Introductionmentioning

confidence: 99%

Effect of process parameters on surface texture generated by laser polishing of additively manufactured Ti-6Al-4V

Solheid¹,

Elkaseer

Wunsch

et al. 2020

Laser-Based Micro- And Nanoprocessing XIV

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Although there have been numerous attempts to define how different laser polishing parameters affect the generated surface roughness, there has been no detailed investigation of how their effects can be combined to optimize the process. This paper applies statistical analysis to model and predict the resulting surface roughness for laser post-processing of components made of Ti-6Al-4V and produced by laser powder bed fusion. This model is based on analysis of a wideranging experimental programme investigating how the interaction of the governing parameters, i.e., laser power, number of repetitions, axial feed rate, scanning speed, and focal position, affected surface roughness. The experimental programme was the result of a robust Design of Experiments analysis and experimental analysis using ANOVA. It is expected that the outcomes will contribute towards the understanding of how the governing parameters influence the laser polishing process and final surface roughness, and would be a tool for optimizing their selection. The results of the ANOVA (analysis of variance) revealed that the most significant parameters are scanning speed followed by laser power and then axial feed rate. In addition, a clear tendency for the estimated Ra to decrease with the increase in laser power at lower values of axial feed rate and of scanning speed, and a focal position in the region of 2 mm. It is noted that the process parameters were varied over wide ranges, including extreme values, which made it difficult to accurately model the dependent variable over the full range of experimental trials.

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Multiphysics modelling of lack-of-fusion voids formation and evolution in IN718 made by multi-track/multi-layer L-PBF

Cited by 168 publications

References 55 publications

Numerical study of the impact of vaporisation on melt pool dynamics in Laser Powder Bed Fusion - Application to IN718 and Ti–6Al–4V

Numerical study of the impact of vaporisation on melt pool dynamics in Laser Powder Bed Fusion - Application to IN718 and Ti–6Al–4V

Dimensional Errors Due to Overhanging Features in Laser Powder Bed Fusion Parts Made of Ti-6Al-4V

Effect of process parameters on surface texture generated by laser polishing of additively manufactured Ti-6Al-4V

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