LAUSR

Abstract An experimental apparatus was designed to reproduce a resistance spot welding operation and allow observation via infrared camera. A specific ex situ device was used to measure the variations of electrical contact resistances, versus pressure and temperature, for the electrode-sheet and sheet–sheet interfaces. The high values of the electrical contact resistances associated to the Al-Si coated Press Hardened Steel sheet explains the spark effect observed at these interfaces by infrared thermography. The initiation and the growth of the nugget from the Al-Si coated sheet to the galvanized low carbon thin sheet are also due to these high contact resistances. The different observation methods and measurements concur to explain the nugget formation.