PSI - Issue 7

Benoît Bracquart et al. / Procedia Structural Integrity 7 (2017) 242–247 B. Bracquart et al. / Structural Integrity Procedia 00 (2017) 000–000

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Concerning the impact of defect size, the small grain microstructure is observed to be more sensitive. Also, when the ratio between the defect size d and the grain size φ is held constant, the plastic strain range associated with a 50% crack initiation probability is equivalent for both grain sizes. This suggests a strong connection between fatigue crack initiation and plasticity. A complementary study of the influence of the defect surroundings microstructure is in progress, using Electron BackScattered Di ff raction (EBSD), to try and link initiation scatter to local microstructure, in particular crystallographic orientations.

Acknowledgments

This work was financially supported by Institut Carnot ARTS and Re´gion Pays de la Loire.

References

[1] R.S. Qi, M. Jin, X.G. Liu and B.F. Guo, 2016. Formation Mechanism of Inclusion Defects in Large Forged Pieces, J Iron Steel Res Int 23, 531–538. [2] H. Dehmani, C. Brugger, T. Palin-Luc, C. Mareau and S. Koechlin, 2016. Experimental study of the impact of punching operations on the high cycle fatigue strength of FeSi thin sheets, Int J Fatigue 82, 721–729. [3] E. Pessard, B. Abrivard, F. Morel, F. Abroug, P. Delhaye, 2014. The e ff ect of quenching and defects size on the HCF behaviour of Boron steel, Int J Fatigue 68, 80–89. [4] J.O. Peters, B.L. Boyce, A.W. Thompson, R.O. Ritchie, O. Roder, 2000. Role of foreign-object damage on thresholds for high cycle fatigue in Ti-6Al-4V, Metall Mater Trans A 31, 1571–1583. [5] Y. Murakami and M. Endo, 1994. E ff ects of defects, inclusions and inhomogeneities on fatigue strength, Int J Fatigue 16, 163–182. [6] M. Endo and Y. Murakami, 1987. E ff ects of an Artificial Small Defect on Torsional Fatigue Strength of Steels, J Eng Mater Tech 109, 124–129. [7] P. Luka´s, L. Kunz, B. Weiss, R. Stickler, 1989. Notch size e ff ect in fatigue, Fatigue Fract Eng Mater Struct 12, 175–186. [8] H.W. Ho¨ppel, L. May, M. Prell and M. Go¨ken, 2011. Influence of grain size and precipitation state on the fatigue lives and deformation mechanisms of CP aluminium and AA6082 in the VHCF-regime, Int J Fatigue 33, 10–18. [9] A. Ja¨rvenpa¨a¨, L.P. Karjalainen and M. Jaskari, 2014. E ff ect of grain size on fatigue behavior of Type 301LN stainless steel, Int J Fatigue 65, 93–98. [10] G.J. Deng, S.T. Tu, X.C. Zhang, Q.Q. Wang and C.H. Qin, 2015. Grain size e ff ect on the small fatigue crack initiation and growth mechanisms of nickel-based superalloy GH4169, Eng Fract Mech 134, 433–450. [13] J. Saga, M. Hayashi and Y. Nishio, 1977. E ff ect of Grain Size on Fatigue Damage in Pure Aluminium, J Soc Mater Sci Japan 26, 289–295. [14] R. Guerchais, 2014. Influence of defects and loading paths on the high cycle fatigue behavior of an austenitic stainless steel 316L, Ph.D Thesis, ENSAM, France. [15] C.A. Sweeney, W. Vorster, S.B. Leen, E. Sakurada, P.E. McHugh and F.P.E. Dunne, 2013. The role of elastic anisotropy, length scale and crystallographic slip in fatigue crack nucleation, J Mech Phys Solids 61, 1224–1240. [16] V.V.C. Wan, D.W. MacLachlan, F.P.E. Dunne, 2014. A stored energy criterion for fatigue crack nucleation in polycrystals, Int J Fatigue 68, 90–102. [17] R.W. Karry and T.J. Dolan, 1953. Influence of grain size on fatigue notch-sensitivity, ASTM Proceeding, 789–804. [18] P. Lorenzino and A. Navarro, 2015. Grain size e ff ects on notch sensitivity, Int J Fatigue 70, 205–215. [19] M. Vincent, Y. Nadot, C. Nadot-Martin and A. Dragon, 2016 Interaction between a surface defect and grain size under high cycle fatigue loading: Experimental approach for Armco iron, Int J Fatigue 87, 81–90. [20] A. Giese, A. Styczynski and Y. Estrin, 1990. Cyclic hardening behaviour of polycrystalline aluminium under tension-compression, Mater Sci Eng A 124, L11–L13. [21] M. Videm and N. Ryum, 1996. Cyclic deformation and fracture of pure aluminium polycrystals, Mater Sci Eng A 219, 11–20. [11] K.S. Chan, 2010. Roles of microstructure in fatigue crack initiation, Int J Fatigue 32, 1428–1447. [12] A.W. Thompson and W.A. Backofen, 1971. The e ff ect of grain size on fatigue, Acta Metall 19, 597–606.