Influence of raceway surface finish on white etching crack generation in WEC critical oil under rolling-sliding conditions

Abstract

In this work, cylindrical roller thrust bearings (CRTBs) with different raceway surface finishes were life tested under rolling-sliding conditions in WEC critical oil. After testing, white etching cracks (WECs) had formed in the raceways of the commercially available standard CRTBs from the test rig manufacturer. However, after embedded abrasive particles were introduced into the raceways (from the lapping process), neither the post-test raceways nor the rollers had WECs, and the damage mode had changed.When the embedded particles were removed by a polishing step, the raceways again showed damage from WECs. The WEC-damaged raceways had “hump”-like raised areas on their tribosurfaces, and each raised area had WECs underneath it. The raised areas were observed to be the locations of surface cracking or spalls.Although WECs are generated in the subsurface, their formation depends on the surface quality of the raceways, and the results suggest that WECs formation is surface driven phenomena. Owing to its fatigue resistance, case-carburized 3310 steel showed significant life improvement in WEC critical oil and in rolling-sliding conditions, irrespective of the damage mode.