Small scale tribology and microstructure evolution in PearliteTuesday (27.09.2016) 15:30 - 15:45 Part of:
To understand macroscopic tribology, the detailed small-scale mechanisms, e.g. microstructure and surface evolution, have to be investigated. The small-scale mechanisms of the two contacting bodies are dominated by the interactions of microasperities, which originate from surface production, microstructural differences in hardness, etc. Macroscopic wear resistant surfaces rely on the tailored evolution of surface layers, i.e. microstructure evolution, which reduce the friction coefficient and
prevent wear particle formation. We study pearlitic steel with 1.6% carbon concentration. Its microstructure consists of hard cementite lamellae embedded in a soft ferrite matrix and it is used in many industrial applications. We prepared the samples by conventional metallography and we deformed the surface with a nanoindenter with spherical diamond tips of different radii and with varying forces and velocities. Afterwards the surfaces are covered by a protective layer of nickel. Tribology induced mechanical surface layers underneath the scratches are investigated, after target preparation, in the scanning electron microscope, transmission electron microscope and via electron backscatter diffraction. We discuss the cementite lamellae fracture and bending as well as the surface layer thickness and morphology as a function of the local loading.