Modelling turbulent thermofluid flow in stationary gas tungsten arc weld pools

Hong, Ki‐Ha; Weckman, D. C.; Strong, A. B.; Zheng, Weimin

doi:10.1179/136217102225002619

Cited by 41 publications

(49 citation statements)

References 24 publications

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“…The turbulence Reynolds number (TRN), defined as the ratio l t /l, is an indicator of turbulence in the weld pool. Hong et al [38,39] found the weld pool to be turbulent for a local value of TRN of 7.9. Because The free surface in the keyhole region is governed mainly by the instantaneous vaporization of the metal and the consequent energy balance at the keyhole walls.…”

Section: B Calculated Velocity and Temperature Fieldsmentioning

confidence: 98%

A Convective Heat-Transfer Model for Partial and Full Penetration Keyhole Mode Laser Welding of a Structural Steel

Naresh

Kelly

Martukanitz

et al. 2007

Metall Mater Trans A

103

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In the keyhole mode laser welding of many important engineering alloys such as structural steels, convective heat transport in the weld pool significantly affects temperature fields, cooling rates, and solidification characteristics of welds. Here we present a comprehensive model for understanding these important weld parameters by combining an efficient keyhole model with convective three-dimensional (3-D) heat-transfer calculations in the weld pool for both partial and full penetration laser welds. A modified turbulence model based on PrandtlÕs mixing length hypotheses is included to account for the enhanced heat and mass transfer due to turbulence in the weld pool by calculating spatially variable effective values of viscosity and thermal conductivity. The model has been applied to understand experimental results of both partial and full penetration welds of A131 structural steel for a wide range of welding speeds and input laser powers. The experimentally determined shapes of the partial and full penetration keyhole mode laser welds, the temperature profiles, and the solidification profiles are examined using computed results from the model. Convective heat transfer was the main mechanism of heat transfer in the weld pool and affected the weld pool geometry for A131 steel. Calculation of solidification parameters at the trailing edge of the weld pool showed nonplanar solidification with a tendency to become more dendritic with increase in laser power. Free surface calculation showed formation of a hump at the bottom surface of the full penetration weld. The weld microstructure becomes coarser as the heat input per unit length is increased, by either increasing laser power or decreasing welding velocity.

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Section: B Calculated Velocity and Temperature Fieldsmentioning

confidence: 98%

A Convective Heat-Transfer Model for Partial and Full Penetration Keyhole Mode Laser Welding of a Structural Steel

Naresh

Kelly

Martukanitz

et al. 2007

Metall Mater Trans A

103

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“…Choo et al [22] analyzed both laminar and turbulent flow behavior of liquid metal in the weld pool. Hong et al [25,26] used the k-e turbulence model to analyze the liquid-metal flow and, subsequently, reported a vorticity-based turbulence model to reduce the computational time in stationary gas tungsten arc weding. DebRoy and coworkers used a three-dimensional (3-D) heat-transfer and fluid-flow analysis based on the finitevolume method to explain various features in the weld pool, considering both arc and laser welding.…”

Section: Introductionmentioning

confidence: 99%

“…Significant efforts are also made to develop convective heat transport-based model to analyze both heat transfer and fluid flow in the molten-weld pool by solving conservation equations of continuity, momentum, and energy equations under constant pressure field. [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] Oreper et al [19] indicated that the influence of both the Lorenz force (electromagnetic force) and Marangoni force (due to surface tension) could be significant in the overall convective heat transport in the weld pool. Mundra et al [20] reported that the surfacetension coefficient and viscosity would play a significant role in weld-pool development.…”

Section: Introductionmentioning

confidence: 99%

Development of a Three-Dimensional Heat-Transfer Model for the Gas Tungsten Arc Welding Process Using the Finite Element Method Coupled with a Genetic Algorithm–Based Identification of Uncertain Input Parameters

Bag

2008

Metall Mater Trans A

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An accurate estimation of the temperature field in weld pool and its surrounding area is important for a priori determination of the weld-pool dimensions and the weld thermal cycles. A finite element-based three-dimensional (3-D) quasi-steady heat-transfer model is developed in the present work to compute temperature field in gas tungsten arc welding (GTAW) process. The numerical model considers temperature-dependent material properties and latent heat of melting and solidification. A novelty of the numerical model is that the welding heat source is considered in the form of an adaptive volumetric heat source that confirms to the size and the shape of the weld pool. The need to predefine the dimensions of the volumetric heat source is thus overcome. The numerical model is further integrated with a parent-centric recombination (PCX)-operated generalized generation gap (G3) model-based genetic algorithm to identify the magnitudes of process efficiency and arc radius that are usually unknown but required for the accurate estimation of the net heat input into the workpiece. The complete numerical model and the genetic algorithm-based optimization code are developed indigenously using an Intel Fortran Compiler. The integrated model is validated further with a number of experimentally measured weld dimensions in GTA-welded samples in stainless steels.

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“…The second approach, such as the one presented in the present paper, uses analytical models to simulate the heat source and material supply: arc plasma phenomena are not explicitly modelled. Over the years, the simplified Goldak approach and the laminar flow analysis in the weld pool have tended to be replaced by more physically coupled models including a Gaussian surface heat flux and turbulent flows without any enhanced viscosity [9,10,11,12]. However the modelling of turbulent flows has only been proposed in steady conditions, for a coordinate system moving with the heat source.…”

Section: Introductionmentioning

confidence: 99%

A level set approach for the simulation of the multipass hybrid laser/GMA welding process

Desmaison¹,

Bellet²,

Guillemot³

2014

Computational Materials Science

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A new 3D finite element model, developed in a level set approach, is proposed to model hybrid gas metal arc / laser welding in multipass conditions. This heat and mass transfer model couples the resolution of the heat conservation equation, the momentum and mass conservation equations and the weld bead development. The arc welding total power is divided in two parts: one corresponding to the energy transferred to the fusion zone by droplets of melted filler material, the rest being transferred to the workpiece by the surrounding plasma. The droplets energy input is modelled as a volumetric heat source. Regarding the heat surface fluxes associated with plasma and laser heating, the "Continuum Surface Force" approach is used to model them as volumetric heat sources concentrated in the immediate neighbourhood of the metal-gas interface. A resolution scheme, consisting in ignoring high velocity fluid flow in the fusion zone, through the use of an augmented liquid viscosity, is proposed and discussed. Accordingly, the liquid thermal conductivity is enhanced to result in a realistic heat transfer to the workpiece. The formation of the weld bead is obtained through the introduction of a source term in the mass conservation equation, and the application of the normal component of surface tension forces, proportional to the mean curvature of the metal-gas interface. This approach is proposed to reduce computation time. The resolution scheme is applied to the simulation of hybrid welding of 18MND5 (ASME SA 533) steel grade. Results are compared to experimental measurements and observations operated in conditions close to industrial ones. The influence of the enhancement applied to the liquid conductivity coefficient is shown and discussed. A strong sensitivity evolution is demonstrated when varying it from the physical value to the value proposed in the welding literature. As proposed, the simplified resolution scheme leads to a good estimation of the weld bead surface development. Nevertheless, there are still noticeable differences with the whole set of experimental results that are discussed and can be explained by model limitations and insufficient knowledge of material and interfacial properties.

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Modelling turbulent thermofluid flow in stationary gas tungsten arc weld pools

Cited by 41 publications

References 24 publications

A Convective Heat-Transfer Model for Partial and Full Penetration Keyhole Mode Laser Welding of a Structural Steel

A Convective Heat-Transfer Model for Partial and Full Penetration Keyhole Mode Laser Welding of a Structural Steel

Development of a Three-Dimensional Heat-Transfer Model for the Gas Tungsten Arc Welding Process Using the Finite Element Method Coupled with a Genetic Algorithm–Based Identification of Uncertain Input Parameters

A level set approach for the simulation of the multipass hybrid laser/GMA welding process

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