Modelling of thermal behaviour in niobium during electron beam welding

Abstract

Niobium (Nb) has been the subject of extensive research for its application as a crucial material for various complex engineering systems. The increased usage of Nb has prompted extensive research into new ways to join it. Previous works done by researchers on niobium joining majorly involves the use of laser welding technology. In recent years, electron beam welding (EBW) has emerged as one of the most effective joining methods, with a poor understanding of the dynamics though. This study aimed to enhance our understanding of the EBW of Nb plates through the development of a novel finite-element multiphysics model and a molecular dynamics analysis. To understand the heat transmission during the welding process, this study developed heat distribution and temperature contour maps. Variations of several process parameters on heat distribution and beam stabilisation were also noted during the finite element analysis. This study also comprehends the physics behind the creation of keyhole geometry. Molecular dynamics analysis introduced Voronoi clusters and radial distribution function graphs to explain the successful macro- and atomistic evolution of the heat distribution during electron beam welding of pure niobium. The research in this literature discusses the experimentation correlated with computational and molecular dynamics modelling. The finite element modelling and the atomistic simulation provide the relation between heat dissipation through the liquid and solid phases of pure Nb and its behaviour at the molecular level. Niobium has a growing future potential in various engineering domains ranging from uses in spacecraft structures to heavy drilling machinery due to its astonishing thermal properties. These structures perform in extreme thermal conditions and thus addition of niobium in these systems can improve their integrity under such environment. EBW has proven to be a very efficient method for joining of materials and thus can be used for highly sophisticated equipment with marginal error. The studies can help provide useful insight in joining of Niobium and its alloys with near perfection which have been used extensively in recent times.