Simulation of Laser Beam Melting of Steel Powders using the Three-Dimensional Volume of Fluid Method

Gürtler, Franz-Josef; Karg, Michael; Leitz, Karl-Heinz; Schmidt, Michael

doi:10.1016/j.phpro.2013.03.162

Cited by 148 publications

(63 citation statements)

References 10 publications

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“…In [9], Gutler et al employ a volume of fluid method (VOF) and were the first to show more realism with a 3D mesoscopic model of melting and solidification. However, a single size powder arranged uniformly was represented at a coarse resolution that does not resolve the point contacts between the particles.…”

Section: Introductionmentioning

confidence: 99%

Laser powder-bed fusion additive manufacturing: Physics of complex melt flow and formation mechanisms of pores, spatter, and denudation zones

et al. 2016

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This study demonstrates the significant effect of the recoil pressure and Marangoni convection in laser powder bed fusion (L-PBF) of 316L stainless steel. A three-dimensional high fidelity powder-scale model reveals how the strong dynamical melt flow generates pore defects, material spattering (sparking), and denudation zones. The melt track is divided into three sections: a topological depression, a transition and a tail region, each being the location of specific physical effects. The inclusion of laser ray-tracing energy deposition in the powder-scale model improves over traditional volumetric energy deposition. It enables partial particle melting, which impacts pore defects in the denudation zone. Different pore formation mechanisms are observed at the edge of a scan track, at the melt pool bottom (during collapse of the pool depression), and at the end of the melt track (during laser power ramp down). Remedies to these undesirable pores are discussed. The results are validated against the experiments and the sensitivity to laser absorptivity is discussed.2

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Section: Introductionmentioning

confidence: 99%

Laser powder-bed fusion additive manufacturing: Physics of complex melt flow and formation mechanisms of pores, spatter, and denudation zones

et al. 2016

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“…Computational Fluid Dynamics (CFD) coupled with a FE analysis has been used to account for thermo-fluid effects inside the melt pool but due to their inherent computational cost are limited to mesoscale simulations for small time scales [23][24][25][26]. Hodge et al [18] advanced this area by incorporating a multi-phase stress term using volumetric fractions, and a phase expansion term to account for volumetric shrinkage during phase change between powder and consolidated form.…”

Section: Introductionmentioning

confidence: 99%

Understanding the effect of laser scan strategy on residual stress in selective laser melting through thermo-mechanical simulation

Parry

Ashcroft

Wildman

2016

Additive Manufacturing

421

287

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A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription. Abstract: Selective laser melting (SLM) is an attractive technology, enabling the manufacture of customised, complex metallic designs, with minimal wastage. However, uptake by industry is currently impeded by several technical barriers, such as the control of residual stress, which have a detrimental effect on the manufacturability and integrity of a component. Indirectly, these impose severe design restrictions and reduce the reliability of components, driving up costs. This paper uses a thermo-mechanical model to better understand the effect of laser scan strategy on the generation of residual stress in SLM. A complex interaction between transient thermal history and the build-up of residual stress has been observed in the two laser scan strategies investigated. The temperature gradient mechanism was discovered for the creation of residual stress. The greatest stress component was found to develop parallel to the scan vectors, creating an anisotropic stress distribution in the part. The stress distribution varied between laser scan strategies and the cause has been determined by observing the thermal history during scanning. Using this, proposals are suggested for designing laser scan strategies used in SLM. Abstract:Selective laser melting (SLM) is an attractive technology, enabling the manufacture of customised, complex metallic designs, with minimal wastage. However, uptake by industry is currently impeded by several technical barriers, such as the control of residual stress, which have a detrimental effect on the manufacturability and integrity of a component. Indirectly, these impose severe design restrictions and reduce the reliability of components, driving up costs. This paper uses a thermomechanical model to better understand the effect of laser scan strategy on the generation of residual stress in SLM. A complex interaction between transient thermal history and the build-up of residual stress has been observed in the two laser scan strategies investigated. The temperature gradient mechanism was discovered for the creation of residual stress. The greatest stress component was found to develop parallel to the scan vectors, creating an anisotropic stress distribution in the part. The stress distribution varied between laser scan strategies and the cause has been determined by observing the thermal history during scanning. Using this, proposals are suggested for designing laser scan strategies used in SLM. Nomenclature:Specific

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“…In this sense, electron beam melting and laser beam melting are specifically investigated in [15][16][17]. Concerning this work, only conduction is considered as heat transportation mechanism within the microscale simulation model.…”

Section: Microscale Simulationmentioning

confidence: 99%

Investigations on Temperature Fields during Laser Beam Melting by Means of Process Monitoring and Multiscale Process Modelling

Schilp

Seidel

Krauss

et al. 2014

Advances in Mechanical Engineering

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Process monitoring and modelling can contribute to fostering the industrial relevance of additive manufacturing. Process related temperature gradients and thermal inhomogeneities cause residual stresses, and distortions and influence the microstructure. Variations in wall thickness can cause heat accumulations. These occur predominantly in filigree part areas and can be detected by utilizing off-axis thermographic monitoring during the manufacturing process. In addition, numerical simulation models on the scale of whole parts can enable an analysis of temperature fields upstream to the build process. In a microscale domain, modelling of several exposed single hatches allows temperature investigations at a high spatial and temporal resolution. Within this paper, FEMbased micro-and macroscale modelling approaches as well as an experimental setup for thermographic monitoring are introduced. By discussing and comparing experimental data with simulation results in terms of temperature distributions both the potential of numerical approaches and the complexity of determining suitable computation time efficient process models are demonstrated. This paper contributes to the vision of adjusting the transient temperature field during manufacturing in order to improve the resulting part's quality by simulation based process design upstream to the build process and the inline process monitoring.

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Simulation of Laser Beam Melting of Steel Powders using the Three-Dimensional Volume of Fluid Method

Cited by 148 publications

References 10 publications

Laser powder-bed fusion additive manufacturing: Physics of complex melt flow and formation mechanisms of pores, spatter, and denudation zones

Laser powder-bed fusion additive manufacturing: Physics of complex melt flow and formation mechanisms of pores, spatter, and denudation zones

Understanding the effect of laser scan strategy on residual stress in selective laser melting through thermo-mechanical simulation

Investigations on Temperature Fields during Laser Beam Melting by Means of Process Monitoring and Multiscale Process Modelling

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