Multiscale study of microstructural evolution and damage in rail steels

In this PhD thesis, we investigate the microstructural evolution and damage in different steel grades used in railway applications such as switches, crossings and curved tracks, which are the key components in the rail transportation industries around the world. The damage in these components leads to a maintenance cost of billions of Euros per year worldwide and in the worst case scenario it can pose severe safety threats to the passengers. The damage mechanisms in these components depend on the microstructure of the steels used The increasing demand of high speed rail transportation and increasing traffic intensity require a thorough understanding of the damage mechanisms in the currently used steel grades in switches, crossings and curved tracks. This understanding can provide guidelines for the design of sustainable/damage resistant materials with an improved life time. Different rail steels such as fine pearlitic steels (R350HT), cast Hadfield steels and Continuously Cooled Carbide Free Bainitic Steels (CC-CFBS) have been investigated from the macro to the atomic scale to understand the physical mechanisms of the damage in relation with their particular microstructure.