Stefan’s research concerns study and establishment the relations between phase compositions and the localisation and fracture failure behaviour in a boron alloyed steel. The studied steel material is used for ultra-high strength components in the automotive industry. The increased demand for low-weight car structure solutions are based on very strong driving forces such as care for the environment and climate as well as safety considerations. Knowledge and presence of methods for failure predictions in e.g. crashworthiness analyses are necessary prerequisites for optimal use of ultra-high strength materials in car structures..
Faculty opponent was Professor Larsgunnar Nilsson, avdelningen för mekanik och hållfasthetslära, Institutionen för ekonomisk och industriell utveckling, Linköpings universitet, Linköping. The dissertation was chaired by, Professor Mats Oldenburg, Department of Engineering Sciences and Mathematics, Luleå University of Technology.