Simulating chemical mixing and molten pool shape in dissimilar welds using thermal fluid dynamics

International Journal of Heat and Mass Transfer, vol. 226, pp. 125449

Abstract

Estimating the properties of dissimilar metal welded joints made using modern high-energy beam techniques presents significant challenges due to the complex nature of the process. These complexities arise from the different thermal and mechanical properties of the materials involved. The properties of a welded joint are primarily determined by the element mixing and final chemical composition when two dissimilar metals are fused together, or when a dissimilar filler material is used. Hence, a representative model capable of tracking elemental distribution and temperature is essential for accurately estimating the micro-scale and macro-scale mechanical properties of the joint, thus optimising the joining process. In this work, a high-fidelity thermal fluid flow model in the multiComponentlaserbeamFoam computational fluid dynamics (CFD) solver is used to simulate the process of laser beam welding. For this purpose, the joining process of AISI 304 stainless steel with a low alloy steel filler material (G3Si1) is simulated. This framework is rigorously validated with experimental results showing the capabilities of such modelling approach. Different strategies to model the filler and material properties are explored: a stationary filler model, applied through the parent material's thickness, was found to accurately mirror experimental results. This model is then used to study the flow properties, thermocapillary effect, and diffusion on the intermixing of composition, aspects that have not been previously examined in depth. The thermocapillary forces were concluded to be the most significant, dictating the peak composition value, the shape and topology of the molten pool. Diffusion fluxes were found to be negligible and not responsible for the majority of the mixing.

Authors 8

1. Parsa Esmati corresponding

   University of Bristol

   Affiliation as printed

   School of Electrical, Electronic and Mechanical Engineering, University of Bristol, Queen's Building, University Walk, Bristol, BS8 1TR, United Kingdom

2. T.F. Flint

   Henry Royce Institute

   Affiliation as printed

   Henry Royce Institute, Royce Hub Building, Oxford Road, Manchester, M13 9PL, United Kingdom

3. Fatma Akyel Aachen Welding and Joining Institute

   RWTH Aachen University

   Affiliation as printed

   WeldNova GmbH, Unter den Eichen 87, Berlin, 2205, Germany

   Welding and Joining Institute, RWTH Aachen University, Pontstraße 49, Aachen, 52062, Germany

4. Simon Olschok Aachen Welding and Joining Institute

   RWTH Aachen University

   Affiliation as printed

   Welding and Joining Institute, RWTH Aachen University, Pontstraße 49, Aachen, 52062, Germany

5. Uwe Reisgen Aachen Welding and Joining Institute

   RWTH Aachen University

   Affiliation as printed

   Welding and Joining Institute, RWTH Aachen University, Pontstraße 49, Aachen, 52062, Germany

6. Philip Cardiff

   University College Dublin · I-Form Advanced Manufacturing Research Centre

   Affiliation as printed

   I-Form, the SFI Research Centre for Advanced Manufacturing, University College Dublin, School of Mechanical and Materials Engineering, University College Dublin, Dublin, Ireland

7. N.O. Larrosa

   University of Bristol · Tecnalia

   Affiliation as printed

   School of Electrical, Electronic and Mechanical Engineering, University of Bristol, Queen's Building, University Walk, Bristol, BS8 1TR, United Kingdom

   Tecnalia, Parque Científico y Tecnológico de Gipuzkoa, Mikeletegi Pasealekua, 2, Donostia-San Sebastián, E-20009, Spain

8. Nicolò Grilli

   University of Bristol

   Affiliation as printed

   School of Electrical, Electronic and Mechanical Engineering, University of Bristol, Queen's Building, University Walk, Bristol, BS8 1TR, United Kingdom