The introduction of advanced high strengths steels enabled automotive manufacturers to simultaneously reduce weight and increase safety of vehicles. However issues were reported concerning the weldability of these steels. These issues concerned both the manufacturability as well as the performance of resistance spot welded joints. The manufacturability addresses the ability to produce joints in an industrial set up, especially the welding range and the electrode lifetime. The performance includes the post weld hardness and the failure mode of resistance spot welded joints. Both aspects are addressed in the dissertation using experimental data and software to model and simulate welding processes.Materials Science & EngineeringMechanical, Maritime and Materials Engineerin