Modelling the transient behaviours of a fully penetrated gas-tungsten arc weld pool with surface deformation

Numerical analysis of the dynamic behaviours of a gas-tungsten arc (GTA) weld pool with full penetration is of great significance to designing the process control algorithm. In this paper, a three-dimensional transient numerical model is developed to investigate the dynamic behaviours of a fully penetrated GTA weld pool with surface deformation. A body-fitted coordinate system is used to transform the complex physical boundaries resulted from the surface deformation into regular boundaries. A separated algorithm is employed to solve the strongly coupling problems between the surface deformation, fluid flow, and heat transfer. By using the model, the whole gas-tungsten arc welding (GTAW) process (including arc ignition, weld pool formation and growth, penetration, quasi-steady state, and arc extinguishments) are simulated, and the transient development of a three-dimensional weld pool shape and fluid flow inside the pool are obtained. The predicted weld geometry matches the experimental results. It provides useful basic data for the development of sensing and control systems of GTAW.