Measurement of Carbon Levels in Structurally Transformed SAE 52100 Ball Bearing Steel by Microprobe Analysis / Die Messung des Kohlenstoffgehaltes in einem umgewandelten Kugellagerstahl SAE 52100 mittels Mikrosondenanalyse

Rolling contact fatigue in bearings: Multiscale overview

“…24 In addition to carbide dissolution, thin elongated stringers or LCs can be seen, mostly sandwiching WEBs or surrounding WEAs. 2,3,9,12,[18][19][20]22 The depth of the highest density of LCs (300-350 mm) agrees with that of WEBs; such density gradually grows with the number of revolutions. 23 The LCs occupy ,21% of the matrix beside the WEBs, and their carbon content is 1?55-1?65 wt-%.…”

“…3,6,12 Based on the contrast under optical microscope, the phase within them is presumably ferrite. 3 Moreover, both bands have the same carbon content (0·06 wt-%) lower than the matrix (0·55–0·6 wt-%), 20 which is unexpected due to the fact that the bands are reported to have higher hardness. 11,19…”

“…23 The LCs occupy ,21% of the matrix beside the WEBs, and their carbon content is 1?55-1?65 wt-%. 20 While Grabulov et al postulated that the LCs originated from the deformation of primary carbides, Martin et al suggested that they were newly formed because of their large size; hence, reprecipitation was suggested to take place. 12,21 Different mechanisms of carbide dissolution and formation have been introduced by several authors, but not all of them have been confirmed; such mechanisms involve carbon supersaturation and migration, which are fostered by high dislocation or vacancy densities stemming from the severely deformed structure.…”

Elucidating white-etching matter through high-strain rate tensile testing

“…Harder types include layers, spheres, white-etching cracks or 'butterfly' wings, [7][8][9] while softer ones are low-and high-angle bands. [10][11][12][13] In the case of large bearings used in wind turbine gearboxes, white-etching cracks and butterflies can lead to their premature failure through a mechanism called white-structure flaking; the subject has been reviewed extensively. 5,[13][14][15][16] One mechanism that has been suggested for the formation of the WEM is adiabatic shear, 17 which occurs when strain rates associated with localised plasticity in steels exceed about 10 2 s −1 .…”

“…Harder types include layers, spheres, white-etching cracks or ‘butterfly’ wings, 7–9 while softer ones are low- and high-angle bands. 10–13 In the case of large bearings used in wind turbine gearboxes, white-etching cracks and butterflies can lead to their premature failure through a mechanism called white-structure flaking; the subject has been reviewed extensively. 5,13–16…”