Simulation and Experimental Study on Forming Process of Wavy Interface in Electromagnetic Pulse Welding Based on Metallic Jet

Abstract

With the advantages of free the heating and cooling, electromagnetic pulse welding is suitable for joining copper to steel. The microstructure morphology of the wavy interface was represented by the particles trajectory of the smoothed particle hydrodynamics (SPH) model, owing to the rapid welding process. In this study, experimental tests and numerical simulations of smooth particle dynamics were performed to reveal the forming process of a wavy interface and vortex. A salient jet and a re-entrant jet were postulated based on the behavior of metallic jets to similar low-viscosity liquids. These jets were then used to analyze the relationship between the moving behavior of the metal particles and the interface formation. The simulation results showed that some copper particles accelerated and then decelerated to stay at the interface. Some copper particles flowed out of the interface at 20 times the initial velocity to form a high-energy ejection, in the welding direction. The velocity of the copper particles decelerated, accelerating that of the steel particles and generating the front wave, and subsequently, the back wave. The re-entrant jet met the steel stream to form a front vortex, mainly composed of Fe elements, and the steel particles were pressed into the wave trough under the salient jet action to create a back vortex with Cu and Fe elements. Finally, microstructural analyses showed that particles moving in the same direction had a streamline organization. Particles in opposite directions had no significant effect on the organization, but caused a high-density plastic deformation and increased hardness. The experimental data were in good agreement with the simulation results.

Fig. 10 SEM micrograph of wavy interface at: (a) front-wave (b) wave trough (c) back-wave (d) wave crest.