Thermal Fluid Dynamics in Welding Processes

Thermal fluid dynamics in welding encompasses the coupled transport of heat and mass within a molten metal pool under high‐energy heat sources. As the welding arc or beam interacts with the substrate, intense thermal gradients induce surface‐tension‐driven flow (Marangoni convection), buoyancy currents and recoil‐pressure effects, all of which govern the shape, depth and stability of the melt pool. The resultant metal flow dictates solidification rates, microstructural evolution and residual‐stress distribution, thereby influencing joint strength, porosity and defect formation. Advances in high‐speed imaging and computational modelling have revealed transient instabilities such as keyhole collapse and surface‐turbulence events, emphasising the need for precise control of process parameters. Understanding these phenomena is fundamental to optimising welding processes across industries—from shipbuilding and pipeline fabrication to aerospace and energy—ensuring consistent weld quality, minimised distortion and enhanced mechanical performance.

Research from Nature Portfolio

Recent studies have achieved direct, time‐resolved visualisation of melt‐pool flow during arc welding, using synchrotron radiation to track velocities up to 0.5 m s⁻¹. These observations reveal that both bulk turbulence and surface turbulence arise depending on the sign of the temperature‐dependent surface‐tension coefficient, with implications for oxide entrainment and weld integrity. Complementary work has introduced a multi‐component thermal fluid dynamics framework that integrates mass diffusion, surface‐tension variations, buoyancy and phase‐change effects. This model captures melting, vapourisation and condensation in alloys, providing a rigorous basis for predicting composition shifts and melt‐pool morphology under high‐energy beams. Together, these efforts form a unified view of how thermal gradients, fluid flow and chemical heterogeneity interact to shape weld microstructures.

Research from all publishers

Investigations into dissimilar‐metal fusion welding have employed in‐situ X‐ray radiography and magneto‐thermal‐hydrodynamic simulations to elucidate finger‐like protrusions at liquid–liquid interfaces and the role of transient solid phases in mixing. These findings inform strategies for offsetting heat sources to improve joint homogeneity. A mathematical analysis of electron beam divergence and focal‐point location has shown that beam geometry critically determines keyhole formation, penetration depth and thermo‐capillary stability, as well as preferential element evaporation in multi‐component steels. Meanwhile, high‐fidelity gas tungsten arc welding simulations have characterised melt‐pool oscillations under steady and pulsed currents, demonstrating that penetration state transitions induce distinct frequency signatures. Such insights enable non‐invasive monitoring and parameter optimisation to achieve desired weld penetration and minimise defects.

Thermal Fluid Dynamics in Welding Processes publication trend

The graph below shows the total number of articles in thermal fluid dynamics in welding processes across all publications each year (not limited to Nature Index journals).

Technical terms

Thermal fluid dynamics: Study of heat transfer and fluid flow interactions within molten metal during welding.

Melt pool: Region of liquid metal created by a welding heat source, where flow and solidification occur.

Marangoni convection: Surface‐tension‐driven fluid flow induced by temperature gradients along the liquid metal surface.

Keyhole mode: High‐energy welding regime characterised by a vapour‐filled cavity that enhances penetration.

Thermo‐capillary instability: Flow instability arising from temperature‐dependent variations in surface tension within the melt pool.

References

1. Revealing internal flow behaviour in arc welding and additive manufacturing of metals. Nature Communications (2018).
2. A thermal fluid dynamics framework applied to multi-component substrates experiencing fusion and vaporisation state transitions. Communications Physics (2020).
3. Evolution and formation of dissimilar metal interfaces in fusion welding. Acta Materialia (2023).
4. A fundamental investigation into the role of beam focal point, and beam divergence, on thermo-capillary stability and evolution in electron beam welding applications. International Journal of Heat and Mass Transfer (2023).
5. A simulation-based approach to characterise melt-pool oscillations during gas tungsten arc welding. International Journal of Heat and Mass Transfer (2021).