Basic investigation of the electrical contact resistance of copper in the field of resistance welding

Resistance welding is a widely used joining technology on copper materials in the automotive industry, mostly in the field of electrical applications. The electrical contact resistance is one of the main physical effects relevant for the highly dynamic process of resistance welding. This work improves the fundamental understanding of the electrical contact resistance for copper materials, with a focus on dynamic state changes present in resistance welding. A novel determination method is developed which characterizes the effect in form a specific electrical contact resistance during fast heating typical for resistance welding. The new method is used to investigate basic influences on the electrical contact resistance such as the contact pressure, the contact temperature and the contact surface properties. Further it was investigated for the first time, if the specific electrical contact resistance depends on the time-dependent history of the change in contact state.