Abstract
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.
Highlights
IntroductionGas metal arc welding (GMAW) is a fusion-based joining technique that is widely employed in industry to join metallic parts and to produce high-integrity structures
The results indicate a reasonable agreement between numerically predicted and experimentally measured melt-pool shapes
For the process parameters studied in the present work, the melt pool grows over time and reaches a quasi-steady-state condition after about 3 s
Summary
Gas metal arc welding (GMAW) is a fusion-based joining technique that is widely employed in industry to join metallic parts and to produce high-integrity structures. The quality of the joints made using arc welding or the structures made using wire-arc additive manufacturing depend on chosen process parameters, material properties and boundary conditions [1,2,3]. Changes in operating variables can alter the magnitude and distribution of the heat input and forces applied to the molten material in melt pools (such as Marangoni, Lorentz, thermal buoyancy forces and arc plasma shear stresses and pressures), affecting fluid flow in the pool and in turn the properties, structure and quality of products [2]. Correct control of melt-pool behaviour during arc welding is crucial to produce joints with desired properties [4]
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