  The galling mechanism of Tristelle 5183, an Fe-based hardfacing alloy, was
investigated at elevated temperature. The test was performed using a bespoke
galling rig. Adhesive transfer and galling were found to occur, as a result of
shear at the adhesion boundary and the activation of an internal shear plane
within one of the tribosurfaces. During deformation, carbides were observed to
have fractured, as a result of the shear train they were exposed to and their
lack of ductility. In the case of niobium carbides, their fracture resulted in
the formation of voids, which were found to coalesce and led to cracking and
adhesive transfer. A tribologically affected zone (TAZ) was found to form,
which contained nanocrystalline austenite, as a result of the shear exerted
within 30{\mu}m of the adhesion boundaries. The galling of Tristelle 5183
initiated from the formation of an adhesive boundary, followed by sub-surface
shear in only one tribosurface, Following further sub-surface shear, an
internal shear plane is activated. internal shear and shear at the adhesion
boundary continues until fracture occur, resulting in adhesive transfer.
