Process characteristics and influences of production-related disturbances in resistance element welding of hybrid materials with steel cover sheets and polymer core

Abstract

Resistance element welding (REW) is an appropriate thermal-based joining method for joining hybrid materials with other structural steel grades, e.g. high-strength steels. Due to insufficient knowledge on the application of this joining process in combination with these new hybrid materials, deeper investigations were done regarding the suitability of the process and specific boundary conditions. This article introduces by giving a summary of the material properties, the boundary conditions and the welding process itself. Afterwards, the pre-assembly step of the elements and the resulting handling strength of the pre-assembled elements are discussed for two different hybrid material thicknesses. Weldability lobes are compared for REW with and without additional adhesives so that appropriate process parameters are defined. Due to a possible industrial application, relevant production-related disturbance variables are addressed as well. Therefore, the impact on the resulting joint properties, e.g. nugget size, is evaluated for different offsets of the electrodes and different gap sizes between the sheets as well as for both orientations of the polarity. The article closes with a comparison of the resulting load-bearing capacities of the REW-joints with those manufactured by resistance spot shunt welding and self-pierce riveting with semi-hollow rivets.