13th International Conference on Fracture June 16–21, 2013, Beijing, China 1) Irreversible deformation (PSB) forms on the surface specimen at the beginning stage of VHCF in plane stress condition 2) Irreversible deformation can growth or multiplies independently at neighbor grains. After 109 cycles new irreversible deformation (localized plastic strain) per each loading cycle Δε/N is decreasing by increasing number of cycle. 3) Irreversible deformation not only exists on the surface before crack but also in the subsurface volume. 4) Irreversible plastic deformations at subsurface makes easier the fatigue crack initiation. Acknowledgements This research was supported by the grant from the project of Microplasticity and energy dissipation in very high cycle Fatigue (DISFAT, project No. ANR-09-BLAN-0025-09), which funded by the National Agency of Research, France (ANR). Inner discussions of DISFAT project with Prof Mughrabi and other members are great appreciated here. The authors also thank F.Garnier for her participation of SEM observations. References [1] S. Suresh, Fatigue of materials (second edition), Cambridge university press, Cambridge, 1998 [2] Bathias,C.,Pineau, A. Fatigue des matériaux et des Structures, 2008, pp85-246 [3] Mughrabi, H. The Strength of Metals and Alloys, pp.1615-1639, Haasen,P., Gerold, V.,Kostorz, G., (Ed.), Pergamon Press, Oxford, 1980 [4] H. Mughrabi, Microscopic mechanisms of metal fatigue, Strength of Metals and Alloys, 3 (1979), pp. 1615-1638 [5] Mughrabi, H., Herz, K., Stark, X. (1976) Int Journal of Fracture 17,193-320 [6] Mughrabi, H., Wüthrich, Ch. (1976) Philosophical Magazine A33, 963-984 [7] Mughrabi, H., Ackermann, F., Herz, K. (1979) In: ASTM STP 675, pp 69-105 [8] Klesnil, M., Lukas, P. (1965) J. of the Iron and Steel Institute 203, 1043 – 1048 [9] Sommer, C., Mughrabi, H., Lockner, D. (1998) Acta Mater. 46, 1527-1536 [10] J.T.Mcgrath, W.J.bratina, Dislocation structures in fatigued iron-carbon alloys, The Philosophical Magazine, 12, 1293-1305,1965. [11] Wood, W. A. ; Reimann, W. H. ; Sargant, K. R. Comparison of Fatigue Mechanisms in Bcc Iron and Fcc Metals, Transactions of the Metallurgical Society of AIM vol. 230, 511-518, 1964. [12] R. P. Wei, A. J. Baker, Observation of dislocation loop arrays in fatigued polycrystalline pure iron, Philosophical Magazine, vol.12, 1087-1091,1965 [13] C. Wang, D. Wagner, Q.Y. Wang, C. Bathias. Gigacycle fatigue initiation mechanism in Armco iron, International Journal of Fatigue, Volume 45, December 2012, Pages 91-97 [14] Chong Wang, Danièle Wagner, Claude Bathias - Study of fatigue crack mechanism on an armco iron in the gigacycle fatigue by temperature recording and microstructural observations, Abstract paper accepted at ICF 13 [15] N. Ranc, D. Wagner, P.C. Paris – Study of thermal effects associated with crack propagation during very high cycle fatigue, Acta Materiala 56 (2008) 4012-4021. [16] Claude Bathias, Paul C. Paris. Gigacycle fatigue of metallic aircraft components. International Journal of Fatigue, Volume 32, Issue 6, June 2010, Pages 894-897
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