Mapping flow evolution in gas tungsten arc weld pools

Wu, Fan; Flint, Thomas; Falch, Ken Vidar; Smith, Marcus; Drakopoulos, Michael; Mirihanage, Wajira

doi:10.1016/j.ijheatmasstransfer.2021.121679

Cited by 13 publications

(4 citation statements)

References 34 publications

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“…Molten metal streams from the melt-pool rim collide in the central region and form a complex unsteady asymmetric flow pattern in the pool. A similar flow pattern is observed experimentally in previous independent studies conducted by Wu et al [ 60 ], Zhao et al [ 61 ]. The maximum local molten metal velocity is about 0.7–0.8 m s −1 and corresponds to a Péclet number (

) larger than unity (

), which signifies that advection dominates the energy transfer in the melt pool and that the process cannot be described adequately using a thermal model without considering fluid flow.…”

Section: Resultssupporting

confidence: 89%

The Effect of Groove Shape on Molten Metal Flow Behaviour in Gas Metal Arc Welding

et al. 2021

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One of the challenges for development, qualification and optimisation of arc welding processes lies in characterising the complex melt-pool behaviour which exhibits highly non-linear responses to variations of process parameters. The present work presents a computational model to describe the melt-pool behaviour in root-pass gas metal arc welding (GMAW). Three-dimensional numerical simulations have been performed using an enhanced physics-based computational model to unravel the effect of groove shape on complex unsteady heat and fluid flow in GMAW. The influence of surface deformations on the magnitude and distribution of the heat input and the forces applied to the molten material were taken into account. Utilising this model, the complex thermal and fluid flow fields in melt pools were visualised and described for different groove shapes. Additionally, experiments were performed to validate the numerical predictions and the robustness of the present computational model is demonstrated. The model can be used to explore the physical effects of governing fluid flow and melt-pool stability during gas metal arc root welding.

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) larger than unity (

), which signifies that advection dominates the energy transfer in the melt pool and that the process cannot be described adequately using a thermal model without considering fluid flow.…”

Section: Resultssupporting

confidence: 89%

The Effect of Groove Shape on Molten Metal Flow Behaviour in Gas Metal Arc Welding

et al. 2021

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“…The negative impacts of porosity on the welds are reflected in severely deteriorating the weld products properties, however, this can be mitigated by controlling hydrogen content, air flow rate or the temperature of the environment according to the previously reported results [6]. Besides, thermocapillary force, arc forces, surface tension force and gravity-driven forces have been shown to change not only the flow conditions but also influence behaviour such as pores elimination in fusion-based welding and additive manufacturing processes [9][10][11].…”

Section: Introductionmentioning

confidence: 93%

“…However, the detailed in-situ information about interrelationship of molten metal flow and porosity formation are limited due to the instantaneity of fusion welding process and opacity of metallic materials, when conventional metallographic methods are used to observe the melt pools and weld joints. Synchrotron X-ray imaging has recently become an important way to study the dynamic processes, such as melting and solidification, in the welding and additive manufacturing of metallic alloys [10][11][12][13][14][15][16]. Notably, data collected from real-time X-ray experiments is critical for developing IOP Publishing doi:10.1088/1757-899X/1274/1/012011 2 physically accurate simulation models of dynamic melt pools [17,18].…”

Section: Introductionmentioning

confidence: 99%

Effects of melt pool flow on porosity levels in arc welding

Falch

Drakopoulos

et al. 2023

IOP Conf. Ser.: Mater. Sci. Eng.

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Arc welding is one of the widely used approaches for joining metals. During the arc welding process, an electric arc creates intense heat to fuse metals that forms the melt pool between the parts to be welded together. Intensive flow fields are observable within the fusion weld pools as a result of multiple driving forces. The flow patterns within the melt pool significantly determine the shape of the weld joint and other attributes of the solidified joint, such as microstructure and defects. Porosity is one of the solidification-related defects that can bring a detrimental impact. During the formation and solidification of weld pools, gas bubbles that are formed can be driven in or out from the pool by the flow. In this work, employing in situ synchrotron X-rays, we have observed how different flow conditions and air-liquid interface are contributed to retaining and releasing the gas bubbles that formed during the arc welding. The results suggest that underpinning driving forces, such as electromagnetic forces, act on molten metal to retain the pores inside the weld joints; but, gravity-driven effects can contribute to reduce the porosity, with appropriate process conditions.

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“…Various researchers have studied the plasma arc and the weld pool regions in steady or transient states, via computer simulations [14,15]. Substantial work is available in the study of heat transfer and fluid flow in gas metal arc welding (GMAW) with consumable wire [16][17][18][19][20][21][22], but minimal work can be found for GTAW.…”

Section: Introductionmentioning

confidence: 99%

Modeling of Melt Flow and Heat Transfer in Stationary Gas Tungsten Arc Welding with Vertical and Tilted Torches

et al. 2021

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A 3D numerical simulation was conducted to study the transient development of temperature distribution in stationary gas tungsten arc welding with filler wire. Heat transfer to the filler wire and the workpiece was investigated with vertical (90°) and titled (70°) torches. Heat flux, current flux, and gas drag force were calculated from the steady-state simulation of the arc. The temperature in the filler wire was determined at three different time intervals: 0.12 s, 0.24 s, and 0.36 s. The filler wire was assumed not to deform during this short time, and was therefore simulated as solid. The temperature in the workpiece was calculated at the same intervals using heat flux, current flux, gas drag force, Marangoni convection, and buoyancy. It should be noted that heat transfer to the filler wire was faster with the titled torch compared to the vertical torch. Heat flux to the workpiece was asymmetrical with both the vertical and tilted torches when the filler wire was fully inserted into the arc. It was found that the overall trends of temperature contours for both the arc and the workpiece were in good agreement. It was also observed that more heat was transferred to the filler wire with the 70° torch compared with the 90° torch. The melted volume of the filler wire (volume above 1750 °K) was 12 mm3 with the 70° torch, compared to 9.2 mm3 with the 90° torch.

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Mapping flow evolution in gas tungsten arc weld pools

Cited by 13 publications

References 34 publications

The Effect of Groove Shape on Molten Metal Flow Behaviour in Gas Metal Arc Welding

The Effect of Groove Shape on Molten Metal Flow Behaviour in Gas Metal Arc Welding

Effects of melt pool flow on porosity levels in arc welding

Modeling of Melt Flow and Heat Transfer in Stationary Gas Tungsten Arc Welding with Vertical and Tilted Torches

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