Influence of Surface Topography on Galling During Hot Forming of Al-Si Coated Ultra High Strength Steel

Abstract: The aim of this Bachelor’s Thesis was to perform a tribological study to evaluate the effects of surface roughness on galling in hot forming of ultra high strength steel. The tribological tests were carried out using an Optimol SRV high temperature reciprocating friction and wear tester with a pin-ondisc configuration. The pin was made from tool steel and the disc from Al-Si coated ultra high strength steel.
The influence of the surface roughness as well as the sliding direction (parallel or perpendicular) with respect to the roughness lay on the tool steel surface was investigated. The specimens were analysed using scanning
electron microscopy (SEM) in order to qualitatively estimate the severity of material transfer (galling) and provide an insight into how the surface topography of the tool steel affect this phenomenon.
The results have shown that reducing the tool specimen surface roughness reduces the severity of galling. Furthermore, sliding parallel to the tool specimen surface roughness lay reduces the severity of galling.