Confirming dark groove microstructural alterations as WEC initiation first stage in cylindrical roller thrust bearings lubricated with WEC critical oil

Abstract

In a recent work, after conducting disc-on-disc tests under the influence of hydrogen, the authors identified microstructure alterations, the so-called dark grooves, as possible initial stages of WEC formation. In this work, the aim is to investigate whether dark grooves also constitute the initial stages of WEC in cylindrical roller thrust bearings (CRTBs) tested under the influence of WEC-critical oils. BEM simulations of the roller/washer contact were conducted to identify the coordinates of the maximum subsurface shear stresses, the region in which the first stages of failure are likely to start. Subsequently, CRTB tests were carried out, where prematurely stopped bearings were characterized considering the BEM results. The initial signs of failure i.e., the dark grooves consisting of nanopores and nanograins, were found in the maximum subsurface shear stress regions indicated by the BEM simulations.