Deformation and phase transformation in polycrystalline cementite (Fe3C) during single- and multi-pass sliding wear

Cementite (Fe3C) plays a major role in the tribological performance of rail and bearing steels. Nonetheless, current understanding its deformation behavior during wear is limited because it conventionally embedded matrix. Here, we investigate chemical evolution bulk polycrystalline cementite single-pass sliding at contact pressure 31 GPa reciprocating multi-pass 3.3 GPa. The was studied by electron backscatter diffraction for slip trace analysis transmission microscopy. Our results demonstrate activation several mechanisms below surface: dislocation slip, shear band formation, fragmentation, grain boundary sliding, rotation. During wear, ductility enhanced due to confined volume, shear/compression domination, potentially frictional heating. microstructural alterations increase subsurface nanoindentation hardness up 2.7 In addition, report Hägg carbide (Fe5C2) formation uppermost deformed regions after both experiments. Based on X-ray diffraction, as well atom probe tomography, propose potential sources excess carbon that promote phase transformation.