Structural Evolution of Martensitic Steel During Dry Sliding Friction Studied with Synchrotron Radiation

Sliding friction causes significant structural transformations in the subsurface layers of interacting materials. These changes are associated with complicated mechanochemical processes which include but not limited to plastic flow, refinement of structure, increase of dislocation density, oxidation, delamination and formation of wear debris. In this study we attempted to observe some of these processes using synchrotron X-ray diffraction using operando and ex situ approaches. For this reason a special friction tester was used, which allows probing the surface layer of the sample using X-ray microbeam. The research was carried out at Beamline ID13 of the European Synchrotron Radiation Facility. The as-quenched medium-carbon steel AISI-5135 was used in experiments. The effect of friction on X-ray line broadening, texturing and formation of iron oxides was analysed and discussed.