Effect of fluid flow in the weld pool on the numerical simulation accuracy of the thermal field in hybrid welding

• A 3D model is developed to conduct the numerical analysis of the thermal process in laser + GMAW-P hybrid welding.
• The coupled model of fluid flow and heat transfer obviously improves the calculation accuracy of thermal cycles.
• The predicted results of weld cross-section are in good agreement with the experimental measurements.

To further improve the accuracy of the numerical computation of heat affected zone (HAZ) geometry and thermal cycles for hybrid welding, it is necessary to consider the influence of the fluid flow in the weld pool with a keyhole on the hybrid welding temperature field. To this end, the coupled model of heat transfer and fluid flow is developed for the laser + GMAW-P hybrid welding of TCS stainless steel. Based on this coupled model, numerical simulation is conducted to predict the temperature field, the fluid flow in the weld pool of hybrid welding when the quasi-stable keyhole exists, and the thermal cycles in HAZ. Simulation results show that the calculated thermal cycles are more reasonable than those predicted by the pure thermal conduction model. Good agreements are observed between the simulation results and the experimentally measured ones. This investigation clarifies the effect of fluid flow in the weld pool on the temperature field in hybrid welding of TCS stainless steel, thus, contributes to an improved prediction accuracy of thermal cycles and HAZ shape and size.