Premature failure in steel bearing elements due to white etching cracks (WEC) is a current research topic especially in wind turbine gearboxes. The damage pattern in rolling-contact bearings appears around 5-10 % of their predicted lifetime in the form of brittle flaking. Studies have shown that the damage mechanism is often associated with the accumulation of hydrogen in the subsurface region of the bearing. Understanding the factors affecting the diffusion and subsurface accumulation of hydrogen in bearing steel is crucial to develop measures to mitigate or eliminate its detrimental effect.

Within the DFG-project CoLifeHy, research work is currently investigating the major factors affecting the accumulation and trapping of hydrogen in bearing steel. Preliminary work has revealed evident influence of residual stresses on the subsurface accumulation of hydrogen. Thermal desorption spectroscopy (TDS) measurements on tested cylindrical thrust roller bearings (CRTB) with different heating rates will enable calculating hydrogen trapping energies. Measurements of residual stresses and dislocation densities will provide quantitative data on microplastic deformation regions. The experimental data will be fed into a finite element simulation model whose aim is to study the diffusion of hydrogen and obtain qualitative information pertaining to stress-assisted hydrogen diffusion under tribological loading. The objective of this work is to correlate the results of the simulations with full bearing tests to obtain lifetime predictions of bearings suffering premature failure.