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

• Published in: Wear Vol. 422-423; pp. 81 - 93
• Main Authors: Paladugu, Mohanchand, Lucas, Douglas R., Scott Hyde, R.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.03.2019; Elsevier Science Ltd
• Subjects: Bearing races; Bearings; Carburizing; Cracking (fracturing); Damage; Damage mode; Etching; Fatigue cracks; Fatigue strength; Finishes; Fracture mechanics; Lubricant; Metal fatigue; Sliding; Steel; Surface finish; Surface properties; Thrust bearings; White etching cracking; Steel; Bearings; White etching cracking; Damage mode; Lubricant
• ISSN: 0043-1648; 1873-2577
• DOI: 10.1016/j.wear.2019.01.051

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. [Display omitted] •White etching cracks (WECs) did not form when the raceways had embedded abrasive particles.•When the raceways didn’t have any remnant abrasive particles or chemical contamination, WECs formed.•WECs were associated with “hump” like raised areas on tribosurfaces of the raceways.•Although the WECs form in subsurface, their formation is surface driven phenomena.•Case carburized material offered high fatigue resistance against WECs damage mode.