A new approach to compute multi-reflections of laser beam in a keyhole for heat transfer and fluid flow modelling in laser welding

Courtois, Mickaël; Carin, Muriel; Masson, Philippe; Gaied, Sadok; Balabane, Mikhaël

doi:10.1088/0022-3727/46/50/505305

Cited by 151 publications

(71 citation statements)

References 31 publications

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“…p 0 , DH V and R are atmospheric pressure, enthalpy change due to evaporation and universal gas constant, respectively [15][16][17][18]. In order to predict the evolution of melt pool at the beginning of interaction between the heat source and the materials during SLM, one needs to identify all forces presented during the process via the conservation of momentum or Navier-Stokes equation, which was written as…”

Section: Experimental and Modelling Methodsmentioning

confidence: 99%

On the role of melt flow into the surface structure and porosity development during selective laser melting

et al. 2015

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a b s t r a c tIn this study, the development of surface structure and porosity of Ti-6Al-4V samples fabricated by selective laser melting under different laser scanning speeds and powder layer thicknesses has been studied and correlated with the melt flow behaviour through both experimental and modelling approaches. The as-fabricated samples were investigated using optical microscopy (OM) and scanning electron microscopy (SEM). The interaction between laser beam and powder particles was studied by both high speed imaging observation and computational fluid dynamics (CFD) calculation. It was found that at a high laser power and a fixed powder layer thickness (20 lm), the samples contain particularly low porosity when the laser scanning speeds are below 2700 mm/s. Further increase of scanning speed led to increase of porosity but not significantly. The porosity is even more sensitive to powder layer thickness with the use of thick powder layers (above 40 lm) leading to significant porosity. The increase of porosity with laser scanning speed and powder layer thickness is not inconsistent with the observed increase in surface roughness complicated by increasingly irregular-shaped laser scanned tracks and an increased number of discontinuity and cave-like pores on the top surfaces. The formation of pores and development of rough surfaces were found by both high speed imaging and modelling, to be strongly associated with unstable melt flow and splashing of molten material.

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Section: Experimental and Modelling Methodsmentioning

confidence: 99%

On the role of melt flow into the surface structure and porosity development during selective laser melting

et al. 2015

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“…These solid-liquid and liquid-gas interfacial conditions are of importance to be comprehensively understood as they can contribute to the formation of residual stresses and distortions during the welding operation. Over the last two decades, literature has been reported on sophisticated modeling approaches [7][8][9][10][11][12] and experimental techniques [13][14][15][16][17][18] to study the dynamics of the keyhole phenomena during high power density fusion welding technologies, such as laser welding. From a modeling perspective, the interface deformation that leads to keyhole formation during the laser welding has been studied intensively using various numerical techniques, including a volume-of-fluid approach [13,14] and a level set method.…”

mentioning

confidence: 99%

“…From a modeling perspective, the interface deformation that leads to keyhole formation during the laser welding has been studied intensively using various numerical techniques, including a volume-of-fluid approach [13,14] and a level set method. [9] Recently, Courtois et al [9] have proposed a level set approach and included the influence of the electromagnetic field to accurately capture the energy reflection inside the keyhole. However, the methodology is very computationally expensive.…”

mentioning

confidence: 99%

An Integrated Modeling Approach for Predicting Process Maps of Residual Stress and Distortion in a Laser Weld: A Combined CFD–FE Methodology

Turner

Panwisawas

Sovani

et al. 2016

Metall Mater Trans B

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Laser welding has become an important joining methodology within a number of industries for the structural joining of metallic parts. It offers a high power density welding capability which is desirable for deep weld sections, but is equally suited to performing thinner welded joints with sensible amendments to key process variables. However, as with any welding process, the introduction of severe thermal gradients at the weld line will inevitably lead to process-induced residual stress formation and distortions. Finite element (FE) predictions for weld simulation have been made within academia and industrial research for a number of years, although given the fluid nature of the molten weld pool, FE methodologies have limited capabilities. An improvement upon this established method would be to incorporate a computational fluid dynamics (CFD) model formulation prior to the FE model, to predict the weld pool shape and fluid flow, such that details can be fed into FE from CFD as a starting condition. The key outputs of residual stress and distortions predicted by the FE model can then be monitored against the process variables input to the model. Further, a link between the thermal results and the microstructural properties is of interest. Therefore, an empirical relationship between lamellar spacing and the cooling rate was developed and used to make predictions about the lamellar spacing for welds of different process parameters. Processing parameter combinations that lead to regions of high residual stress formation and high distortion have been determined, and the impact of processing parameters upon the predicted lamellar spacing has been presented.

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“…e keyhole oscillates due to the opposition of the dynamic forces and the melt flow. Courtois et al [165] confirmed the findings by Zhao et al by calculating the laser reflections in the keyhole during laser welding.…”

Section: Weld Porositymentioning

confidence: 58%

A Review on Melt‐Pool Characteristics in Laser Welding of Metals

Fotovvati

Wayne

Lewis

et al. 2018

Advances in Materials Science and Engineering

131

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Laser welding of metals involves with formation of a melt-pool and subsequent rapid solidification, resulting in alteration of properties and the microstructure of the welded metal. Understanding and predicting relationships between laser welding process parameters, such as laser speed and welding power, and melt-pool characteristics have been the subjects of many studies in literature because this knowledge is critical to controlling and improving laser welding. Recent advances in metal additive manufacturing processes have renewed interest in the melt-pool studies because in many of these processes, part fabrication involves small moving melt-pools. e present work is a critical review of the literature on experimental and modeling studies on laser welding, with the focus being on the influence of process parameters on geometry, thermodynamics, fluid dynamics, microstructure, and porosity characteristics of the melt-pool. ese data may inform future experimental laser welding studies and may be used for verification and validation of results obtained in future melt-pool modeling studies.

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A new approach to compute multi-reflections of laser beam in a keyhole for heat transfer and fluid flow modelling in laser welding

Cited by 151 publications

References 31 publications

On the role of melt flow into the surface structure and porosity development during selective laser melting

On the role of melt flow into the surface structure and porosity development during selective laser melting

An Integrated Modeling Approach for Predicting Process Maps of Residual Stress and Distortion in a Laser Weld: A Combined CFD–FE Methodology

A Review on Melt‐Pool Characteristics in Laser Welding of Metals

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