Research at MMD

The project focuses on fatigue-resistant, high-strength steel, used in load-carrying beams in the chassis of heavy vehicles.

When high strength bearing steels are exposed to repeated rolling contact cycles at high loads the material below the contact eventually displays changes in the microstructure. The affected volume is small and comprises the highest stressed volume below the contact. The microstructural change of the material is often characterized by dark etching areas after 100 thousand to 100 million cycles followed by white bands after billions of cycles for maximum contact pressures above 3 GPa. It is of interest in the present project to develop a detailed understanding of the microstructural decay and to couple this with fatigue nucleation.

Materials manufactured from powder based technologies, such as compaction and sintering or additive manufacturing, are characterized both by the unique microstructures that can be obtained from different alloying techniques as well as the porosity that is often present in the materials. Thus the models used to analyze these materials must be able to take these factors into account.