Abstract
Multiphase Fe-based hardfacing alloys, for example Tristelle 5183 Fe-21%Cr-10%Ni-7.5%Nb-5%Si-2%C in wt.%, are extensively used for tribological applications, including valves, bearings and drive mechanisms, where two surfaces are unavoidably subjected to loaded sliding contact within engineering systems. In this study, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray diffraction (XRD) were used to characterise, for the first time, the tribologically affected material induced by the self-mated sliding contact of HIPed Tristelle 5183. This provided novel insight into the deformation modes which permit the accumulation of the high levels of subsurface strain required for plasticity dominated (adhesive) wear in a commercial hardfacing. In the subsurface regions furthest from the sliding contact, plastic deformation is accommodated by deformation induced martensitic transformation to ϵ-martensite and α′-martensite, twinning, the generation of planar dislocation arrangements (generated by planar slip) and the generation of dislocation tangles. Closer to the sliding contact, the subsurface becomes unstable, and nanocrystallisation driven by grain boundary mediated deformation mechanisms and crystallographic slip completely engulf the near surface microstructure. It is postulated that nanocrystalisation within the subsurface is a needed in order to accommodate the extremely high strains required in order to permit tribological degradation via plasticity dominated wear. The extrusion of metallic slivers via plastic ratcheting generates ductile shear cracks governed by plastic strain, and the failure of these slivers generates plate/flake-like wear debris.
Original language | English |
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Article number | 146023 |
Number of pages | 18 |
Journal | Materials Science and Engineering A |
Volume | 892 |
DOIs | |
Publication status | Published - Feb 2024 |
MoE publication type | A1 Journal article-refereed |
Funding
The authors gratefully acknowledge funding from Rolls-Royce plc, UK . The authors are also incredibly thankful for the experimental support provided by Dr. Deen Zhang. The authors thank the Nanoscale and Microscale Research Centre (nmRC) for providing access to instrumentation. Access to the JEOL 7100F FEG-SEM was supported by the Engineering and Physical Sciences Research Council (EPSRC) [under grant EP/L022494/1] and the University of Nottingham.
Keywords
- Deformation structures
- Hardfacings
- Nanocrystalline microstructure
- Severe plastic deformation
- Transmission electron microscopy (TEM)
- Tribology