Severe deformation of pearlite during Microscale Tribology

Tribology at the macroscale is the interaction of micrometer asperities as well as the evolution of  microstructures. Wear resistant surfaces depend on an understanding of these evolution mechanisms and on developing tailored surface layers. We investigate the severe microscale deformation mechanisms of pearlitic steel, i.e. the ferrite and cementite composite, during single stroke wear experiments. On the one hand, we perform microtribology experiments using a diamond indenter and observe severe irreversible cementite deformation strains on the order of tens of percent. On the other hand, we use microcantilever experiments with and without a pre-crack. The pre-cracked samples are used to quantify the fracture toughness and observe the fracture mechanisms. The samples without pre-cracks are used to determine the amount of irreversible deformation in the absence of ferrite support. We will discuss the ductility of cementite and argue about the mechanisms that result severe microscale deformation in pearlite.