Tribology Letters

, 67:40 | Cite as

Effect of Retained Austenite on White Etching Crack Behavior of Carburized AISI 8620 Steel Under Boundary Lubrication

  • Sougata Roy
  • Benjamin Gould
  • Ye Zhou
  • Nicholaos G. Demas
  • Aaron C. Greco
  • Sriram SundararajanEmail author
Original Paper


The formation of white etching cracks (WECs) is a dominant failure mode in wind turbine gearbox bearings that can significantly shorten their operating life. Although the phenomenon of WECs has been communicated in the field for more than a decade, the driving mechanisms are still debated, and the impact of proposed mitigation techniques is not quantified. Leading hypotheses to inhibit the formation of WECs center on material solutions, including the use of steel with high levels of retained austenite (RA). The present work aims to explore the impact of RA on the formation of WECs within AISI 8620 steel under boundary lubrication. A three ring-on-roller benchtop test rig was used to replicate WECs in samples with different levels of RA. While varying levels of RA had a minimal effect on time until failure, a significant effect on crack morphology was observed. Additionally, potential underlying mechanisms of White Etching Area formation were elucidated. Under the current test conditions, the microstructural alterations adjacent to the cracks in the lower RA samples were more developed compared to those of the higher RA samples. Additionally, the WEC networks in the high RA samples contained significantly more crack branches than those of the low RA samples.


White etching cracks Retained austenite Rolling contact fatigue Wind turbine gearbox bearings Microstructural alterations Bearing failure 



The authors would like to thank Dr. Maria De La Cinta Lorenzo Martin for her assistance with electron microscopy and Dr. Oyelayo Ajayi for his helpful discussion on metallurgy. Present study is a part of Project funded by John Deere Product Engineering Center in Waterloo, Iowa and Iowa State University. This work was also supported by the US Department of Energy Office of Energy Efficiency and Renewable Energy, Wind Energy Technology Office under Contract No. DE-AC02-06CH11357. The authors are grateful to DOE Project Managers Mr. Michael Derby and Mr. Brad Ring for their support and encouragement. Use of the Center for Nanoscale Materials an Office of Science User Facility was supported by the US Department of Energy Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-06CH11357.


  1. 1.
    Kotzalas, M.N., Doll, G.L.: Tribological advancements for reliable wind turbine performance. Philos. Trans. 368(1929), 4829–4850 (2010)CrossRefGoogle Scholar
  2. 2.
    Musial, W., Butterfield, S., McNiff, B.: Improving wind turbine gearbox reliability. In: European Wind Energy Conference, 2007, Milan Italy, pp. 7–10Google Scholar
  3. 3.
    Greco, A., et al.: Material wear and fatigue in wind turbine systems. Wear 302(1–2), 1583–1591 (2013)CrossRefGoogle Scholar
  4. 4.
    Singh, H., et al.: Investigation of microstructural alterations in low- and high-speed intermediate-stage wind turbine gearbox bearings. Tribol. Lett. 65(3), 81 (2017)CrossRefGoogle Scholar
  5. 5.
    Kang, J.H., et al.: Solute redistribution in the nanocrystalline structure formed in bearing steels. Scr. Mater. 69(8), 630–633 (2013)CrossRefGoogle Scholar
  6. 6.
    Smelova, V., et al.: Electron microscopy investigations of microstructural alterations due to classical Rolling Contact Fatigue (RCF) in martensitic AISI 52100 bearing steel. Int. J. Fatigue 98, 142–154 (2017)CrossRefGoogle Scholar
  7. 7.
    Smelova, V., et al.: Microstructural changes in White Etching Cracks (WECs) and their relationship with those in Dark Etching Region (DER) and White Etching Bands (WEBs) due to Rolling Contact Fatigue (RCF). Int. J. Fatigue 100, 148–158 (2017)CrossRefGoogle Scholar
  8. 8.
    Su, Y.-S., et al., Review of the damage mechanism in wind turbine gearbox bearings under rolling contact fatigue. Front. Mech. Eng. (2017). CrossRefGoogle Scholar
  9. 9.
    Su, Y.S., et al.: Deformation-induced amorphization and austenitization in white etching area of a martensite bearing steel under rolling contact fatigue. Int. J. Fatigue 105, 160–168 (2017)CrossRefGoogle Scholar
  10. 10.
    Gould, B., Greco, A.: The influence of sliding and contact severity on the generation of white etching cracks. Tribol. Lett. 60(2), 29 (2015)CrossRefGoogle Scholar
  11. 11.
    Grabulov, A., Petrov, R., Zandbergen, H.W.: EBSD investigation of the crack initiation and TEM/FIB analyses of the microstructural changes around the cracks formed under Rolling Contact Fatigue (RCF). Int. J. Fatigue 32(3), 576–583 (2010)CrossRefGoogle Scholar
  12. 12.
    Grabulov, A., Ziese, U., Zandbergen, H.W.: TEM/SEM investigation of microstructural changes within the white etching area under rolling contact fatigue and 3-D crack reconstruction by focused ion beam. Scr. Mater. 57(7), 635–638 (2007)CrossRefGoogle Scholar
  13. 13.
    Martin, J.A., Borgese, S.F., Ad, E.: Microstructural alterations of rolling—bearing steel undergoing cyclic stressing. J. Basic Eng. 88(3), 555 (1966)CrossRefGoogle Scholar
  14. 14.
    Obrien, J.L., King, A.H.: Electron microscopy of stress-induced structural alterations near inclusions in bearing steels. J. Basic Eng. 88(3), 568 (1966)CrossRefGoogle Scholar
  15. 15.
    Lund, T.B., Beswick, J., Dean, S.W.: Sub-surface initiated rolling contact fatigue—influence of non-metallic inclusions. J. ASTM Int. 7(5), 102559 (2010)CrossRefGoogle Scholar
  16. 16.
    Scott, D., Loy, B., Mills, G.H.: Paper 10: metallurgical aspects of rolling contact fatigue. In: Proceedings of the Institution of Mechanical Engineers, pp. 94–103. SAGE Journals (1966)Google Scholar
  17. 17.
    Stadler, K., Lai, J., Vegter, R., A review: the dilemma with premature white etching crack (WEC) bearing failures. In: Bearing Steel Technologies: Advances in Steel Technologies for Rolling Bearings, vol. 10, pp. 487–508. ASTM International, West Conshohocken (2015)Google Scholar
  18. 18.
    Evans, M.H.: An updated review: white etching cracks (WECs) and axial cracks in wind turbine gearbox bearings. Mater. Sci. Technol. 32(11), 1133–1169 (2016)CrossRefGoogle Scholar
  19. 19.
    Luyckx, J.: Hammering wear impact fatigue hypothesis WEC/irWEA failure mode on roller bearings. In: NREL Wind Tribology Seminar (2011)Google Scholar
  20. 20.
    Hyde, S.: White etch areas: metallurgical characterization and atomistic modeling (2014)Google Scholar
  21. 21.
    Solano-Alvarez, W., Bhadeshia, H.K.D.H.: White-etching matter in bearing steel. Part II: distinguishing cause and effect in bearing steel failure. Metall. Mater. Trans. A 45a(11), 4916–4931 (2014)CrossRefGoogle Scholar
  22. 22.
    Bhadeshia, H.K.D.H.: Steels for bearings. Prog. Mater. Sci. 57(2), 268–435 (2012)CrossRefGoogle Scholar
  23. 23.
    Evans, M.H., et al.: Serial sectioning investigation of butterfly and white etching crack (WEC) formation in wind turbine gearbox bearings. Wear 302(1–2), 1573–1582 (2013)CrossRefGoogle Scholar
  24. 24.
    Bruce, T., et al.: Characterisation of white etching crack damage in wind turbine gearbox bearings. Wear 338, 164–177 (2015)CrossRefGoogle Scholar
  25. 25.
    Gould, B., Greco, A.: Investigating the process of white etching crack initiation in bearing steel. Tribol. Lett. 62(2), 26 (2016)CrossRefGoogle Scholar
  26. 26.
    Errichello, R., et al.: Wind Turbine Tribology Seminar: A Recap (2011)Google Scholar
  27. 27.
    Gegner, J.: Tribological Aspects of Rolling Bearing Failures. INTECH Open Access Publisher, London (2011)CrossRefGoogle Scholar
  28. 28.
    Loos, J., Bergmann, I., Goss, M.: Influence of currents from electrostatic charges on WEC formation in rolling bearings. Tribol. Trans. 59(5), 865–875 (2016)CrossRefGoogle Scholar
  29. 29.
    Gould, B.J., Burris, D.L.: Effects of wind shear on wind turbine rotor loads and planetary bearing reliability. Wind Energy 19, 1011–1021 (2015)CrossRefGoogle Scholar
  30. 30.
    Garabedian, N., et al.: The cause of premature wind turbine bearing failures: overloading or underloading? Tribol. Trans. 61(5), 850–860 (2018)CrossRefGoogle Scholar
  31. 31.
    Kang, Y.S., Evans, R.D., Doll, G.L.: Roller-raceway slip simulations of wind turbine gearbox bearings using dynamic bearing model. In: Proceedings of the STLE/ASME International Joint Tribology Conference, 2010, pp. 407–409 (2011)Google Scholar
  32. 32.
    Holweger, W.: Progresses in Solving White Etching Crack Phenomena. NREL: Gearbox Reliability Collaborative, Golden (2014)Google Scholar
  33. 33.
    Strandell, I., Fajers, C., Lund, T.: Corrosion—one root cause for premature failures. In: 37th Leeds–Lyon Symposium on Tribology (2010)Google Scholar
  34. 34.
    Iso, K., Yokouchi, A., Takemura, H.: Research Work for Clarifying the Mechanism of White Structure Flaking and Extending the Life of Bearings. SAE Technical Paper, 2005(SP-1967), pp. 39–48Google Scholar
  35. 35.
    Vegter, R.H., Slycke, J.T.: The role of hydrogen on rolling contact fatigue response of rolling element bearings. J. ASTM Int. 7(2), 1–12 (2010)CrossRefGoogle Scholar
  36. 36.
    Uyama, H., et al.: The effects of hydrogen on microstructural change and surface originated flaking in rolling contact fatigue. Tribol. Online 6, 123–132 (2011)CrossRefGoogle Scholar
  37. 37.
    Hiraoka, K., et al.: Generation process observation of micro-structural change in rolling contact fatigue by hydrogen-charged specimens. J. Jpn. Soc. Tribol. 52(12), 888–895 (2007)Google Scholar
  38. 38.
    Kino, N., Otani, K.: The influence of hydrogen on rolling contact fatigue life and its improvement. JSAE Rev. 24(3), 289–294 (2003)CrossRefGoogle Scholar
  39. 39.
    Tamada, K., Tanaka, H.: Occurrence of brittle flaking on bearings used for automotive electrical instruments and auxiliary devices. Wear 199(2), 245–252 (1996)CrossRefGoogle Scholar
  40. 40.
    Ciruna, J.A., Szieleit, H.J.: The effect of hydrogen on the rolling contact fatigue life of AISI 52100 and 440C steel balls. Wear 24, 107–118 (1973)CrossRefGoogle Scholar
  41. 41.
    Grunberg, L.: The formation of hydrogen peroxide on fresh metal surfaces. Proc. Phys. Soc. Lond. B 66(399), 153–161 (1953)CrossRefGoogle Scholar
  42. 42.
    Imran, T., Jacobson, B., Shariff, A.: Quantifying diffused hydrogen in AISI-52100 bearing steel and in silver steel under tribo-mechanical action: pure rotating bending, sliding–rotating bending, rolling–rotating bending and uni-axial tensile loading. Wear 261(1), 86–95 (2006)CrossRefGoogle Scholar
  43. 43.
    Ray, D., et al.: Hydrogen embrittlement of a stainless ball-bearing steel. Wear 65(1), 103–111 (1980)CrossRefGoogle Scholar
  44. 44.
    Matsubara, Y., Hamada, H.: A novel method to evaluate the influence of hydrogen on fatigue properties of high strength steels. J. ASTM Int. 3, 1–14 (2006)CrossRefGoogle Scholar
  45. 45.
    Lu, H., et al.: Hydrogen-enhanced dislocation emission, motion and nucleation of hydrogen-induced cracking for steel. Sci. China E 40(5), 530–538 (1997)CrossRefGoogle Scholar
  46. 46.
    Fujita, S., et al.: Effect of hydrogen on Mode II fatigue crack behavior of tempered bearing steel and microstructural changes. Int. J. Fatigue 32(6), 943–951 (2010)CrossRefGoogle Scholar
  47. 47.
    Evans, M.H., et al.: Effect of hydrogen on butterfly and white etching crack (WEC) formation under rolling contact fatigue (RCF). Wear 306(1–2), 226–241 (2013)CrossRefGoogle Scholar
  48. 48.
    Ruellan, A., et al.: Understanding white etching cracks in rolling element bearings: the effect of hydrogen charging on the formation mechanisms. Proc. Inst. Mech. Eng. J 228, 1252–1265 (2014)CrossRefGoogle Scholar
  49. 49.
    Evans, M.H., et al.: White etching crack (WEC) investigation by serial sectioning, focused ion beam and 3-D crack modelling. Tribol. Int. 65, 146–160 (2013)CrossRefGoogle Scholar
  50. 50.
    Guzman, F.G., et al.: Reproduction of white etching cracks under rolling contact loading on thrust bearing and two-disc test rigs. Wear 390–391, 23–32 (2017)CrossRefGoogle Scholar
  51. 51.
    Danielsen, H.K., et al.: Multiscale characterization of White Etching Cracks (WEC) in a 100Cr6 bearing from a thrust bearing test rig. Wear 370, 73–82 (2017)CrossRefGoogle Scholar
  52. 52.
    Richardson, A.D., et al.: The evolution of white etching cracks (WECs) in rolling contact fatigue-tested 100Cr6 steel. Tribol. Lett. 66(1), 6 (2018)CrossRefGoogle Scholar
  53. 53.
    Richardson, A.D., et al.: Thermal desorption analysis of hydrogen in non-hydrogen-charged rolling contact fatigue-tested 100Cr6 steel. Tribol. Lett. 66(1), 4 (2018)CrossRefGoogle Scholar
  54. 54.
    Scepanskis, M., Gould, B., Greco, A.: Empirical investigation of electricity self-generation in a lubricated sliding–rolling contact. Tribol. Lett. 65, 109–119 (2017)CrossRefGoogle Scholar
  55. 55.
    Evans, M.H., et al.: Confirming subsurface initiation at non-metallic inclusions as one mechanism for white etching crack (WEC) formation. Tribol. Int. 75, 87–97 (2014)CrossRefGoogle Scholar
  56. 56.
    Franke, J., et al.: White etching cracking—simulation in bearing rig and bench tests. Tribol. Trans. 61(3), 403–413 (2018)CrossRefGoogle Scholar
  57. 57.
    Gould, B., et al.: The effect of lubricant composition on white etching crack failures. Tribol. Lett. 67(7), 7 (2019)CrossRefGoogle Scholar
  58. 58.
    Paladugu, M., Hyde, R.S.: White etching matter promoted by intergranular embrittlement. Scr. Mater. 130, 219–222 (2017)CrossRefGoogle Scholar
  59. 59.
    Paladugu, M., Hyde, R.S.: Microstructure deformation and white etching matter formation along cracks. Wear 390–391, 367–375 (2017)CrossRefGoogle Scholar
  60. 60.
    Li, S.X., et al.: Microstructural evolution in bearing steel under rolling contact fatigue. Wear 380–381, 146–153 (2017)CrossRefGoogle Scholar
  61. 61.
    Bruce, T., et al.: Formation of white etching cracks at manganese sulfide (MnS) inclusions in bearing steel due to hammering impact loading. Wind Energy 19(10), 1903–1915 (2016)CrossRefGoogle Scholar
  62. 62.
    Gould, B., et al.: An analysis of premature cracking associated with microstructural alterations in an AISI 52100 failed wind turbine bearing using X-ray tomography. Mater. Des. 117, 417–429 (2017)CrossRefGoogle Scholar
  63. 63.
    Gould, B., et al.: Using advanced tomography techniques to investigate the development of White Etching Cracks in a prematurely failed field bearing. Tribol. Int. 116, 362–370 (2017)CrossRefGoogle Scholar
  64. 64.
    Errichello, R., Budny, R., Eckert, R.: Investigations of bearing failures associated with white etching areas (WEAs) in wind turbine gearboxes. Tribol. Trans. 56(6), 1069–1076 (2013)CrossRefGoogle Scholar
  65. 65.
    Paladugu, M., Hyde, R.S.: Influence of microstructure on retained austenite and residual stress changes under rolling contact fatigue in mixed lubrication conditions. Wear 406–407, 84–91 (2018)CrossRefGoogle Scholar
  66. 66.
    Ooi, G.T.C., Roy, S., Sundararajan, S.: Investigating the effect of retained austenite and residual stress on rolling contact fatigue of carburized steel with XFEM and experimental approaches. Mater. Sci. Eng. A 732, 311–319 (2018)CrossRefGoogle Scholar
  67. 67.
    Roy, S., Ooi, G.T.C., Sundararajan, S.: Effect of retained austenite on micropitting behavior of carburized AISI 8620 steel under boundary lubrication. Materialia 3, 192–201 (2018)CrossRefGoogle Scholar
  68. 68.
    Roy, S., Sundararajan, S.: Effect of retained austenite on spalling behavior of carburized AISI 8620 steel under boundary lubrication. Int. J. Fatigue 119, 238–246 (2019)CrossRefGoogle Scholar
  69. 69.
    Roy, S., Sundararajan, S.: The effect of heat treatment routes on the retained austenite and tribomechanical properties of carburized AISI 8620 steel. Surf. Coat. Technol. 308, 236–243 (2016)CrossRefGoogle Scholar
  70. 70.
    Roy, S., White, D., Sundararajan, S.: Correlation between evolution of surface roughness parameters and micropitting of carburized steel under boundary lubrication condition. Surf. Coat. Technol. 350, 445–452 (2018)CrossRefGoogle Scholar
  71. 71.
    Singh, H., et al.: Fatigue resistant carbon coatings for rolling/sliding contacts. Tribol. Int. 98, 172–178 (2016)CrossRefGoogle Scholar
  72. 72.
    Chung, Y.-W.: Introduction to Materials Science and Engineering. CRC Press, Boca Raton (2006)CrossRefGoogle Scholar
  73. 73.
    Zeng, D., et al.: Influence of laser dispersed treatment on rolling contact wear and fatigue behavior of railway wheel steel. Mater. Des. 54, 137–143 (2014)CrossRefGoogle Scholar
  74. 74.
    Dommarco, R.C., et al.: Residual stresses and retained austenite evolution in SAE 52100 steel under non-ideal rolling contact loading. Wear 257(11), 1081–1088 (2004)CrossRefGoogle Scholar
  75. 75.
    Evans, M.H.: White structure flaking (WSF) in wind turbine gearbox bearings: effects of ‘butterflies’ and white etching cracks (WECs). Mater. Sci. Technol. 28(1), 3–22 (2012)CrossRefGoogle Scholar
  76. 76.
    Osterlund, R., et al.: Butterflies in fatigued all bearings—formation mechanism and structure. Scand. J. Metall. 11, 23–32 (1982)Google Scholar

Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  • Sougata Roy
    • 1
  • Benjamin Gould
    • 2
  • Ye Zhou
    • 2
    • 3
  • Nicholaos G. Demas
    • 2
  • Aaron C. Greco
    • 2
  • Sriram Sundararajan
    • 1
    Email author
  1. 1.Department of Mechanical EngineeringIowa State UniversityAmesUSA
  2. 2.Applied Materials DivisionArgonne National LaboratoryArgonneUSA
  3. 3.State Key Laboratory of Mechanical TransmissionsChongqing UniversityChongqingChina

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