Damage Evolution and Crack Growth in Nickel-Based Alloys during Ultrasonic Fatigue

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Abstract:

Experimental results on the fatigue damage of quasi defect-free materials in the VHCF range are presented. For nickel-based superalloys and pure nickel the likelihood of crack initiation at favorable grain morphologies is studied. Slip band and microcrack formation at the surface was observed even in run-out samples. Hence, microcracks were evaluated regarding their propagation capabilities according to grain orientation and barrier function of grain boundaries. In the VHCF regime crack initiation can shift from surface to subsurface, consequently early crack growth has to be studied by means of optical methods and indirect detection techniques or tomographic methods. In the study presented crack initiation and crack growth was monitored through optical observation and quasi 3-D observation by means of synchrotron radiation. For an as-received and a coarse-grained condition of pure nickel Ni201 fatigue crack growth in the VHCF regime occurs at deltaK as low as 3.54 MPam1/2 for a crack growth rate da/dN = 10E-12 m/cycle. The grain size had no effect on the threshold limit but crack growth retardation at grain boundaries and crack path deflection lead to lower crack growth rates for the coarse-grained condition In the nickel-based alloy Nimonic 80A the influence of microstructure on the intercrystalline crack initiation and propagation was confirmed. Here, the combination of the misorientation angle between two adjacent grains and the orientation of their boundary with respect to the external load defines the magnitude of stress concentration at grain boundaries.

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Materials Science Forum (Volumes 783-786)

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2410-2415

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May 2014

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© 2014 Trans Tech Publications Ltd. All Rights Reserved

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[1] S. Stanzl-Tschegg, B. Schönbauer: Mechanisms of strain localization, crack initiation and fracture of polycrystalline copper in the VHCF regime, Int. J. Fatigue 32 (2010) 886-893.

DOI: 10.1016/j.ijfatigue.2009.03.016

Google Scholar

[2] U. Krupp, A. Giertler, M. C. Marinelli, H. Knobbe, H. -J. Christ, P. Köster, C. -P. Fritzen, S. Herenu, I. Alvarez-Armas in: Proc. of the 5th Int. Conf. on VHCF, C. Berger, H. -J. Christ (Eds. ), DVM, Berlin (2011), 127-132.

Google Scholar

[3] Y. Gao, J.S. Stölken, M. Kumar, R.O. Ritchie: High-cycle fatigue of nickel-base superalloy René 104 (ME3): Interaction of microstructurally small cracks with grain boundaries of known character , Acta Mater. 55 (2007) 3155-3167.

DOI: 10.1016/j.actamat.2007.01.033

Google Scholar

[4] L. Liu, N.S. Husseini, C.J. Torbet, D.P. Kumah, R. Clarke, T.M. Pollock, J.W. Jones: In Situ Imaging of High Cycle Fatigue Crack Growth in Single Crystal Nickel-Base Superalloys by Synchrotron X-Radiation J. Eng. Mater. Technol. 130 (2008).

DOI: 10.1115/1.2840966

Google Scholar

[5] J. Miao, T. M. Pollock, J. W. Jones: Microstructural extremes and the transition from fatigue crack initiation to small crack growth in a polycrystalline nickel-base superalloy, Acta Mater. 60 (2012) 2840-2854.

DOI: 10.1016/j.actamat.2012.01.049

Google Scholar

[6] L. Liu, N.S. Husseini, C.J. Torbet, W. -K. Lee, R. Clarke, J.W. Jones, T.M. Pollock: In situ synchrotron X-ray imaging of high-cycle fatigue crack propagation in single-crystal nickel-base alloys, Acta Mater. 59 (2011) 5103-5115.

DOI: 10.1016/j.actamat.2011.04.042

Google Scholar

[7] M. Zimmermann, J. W. Jones: Microstructure and early crack growth of non-ferrous metals in the very high cycle fatigue range, Proc. of the 5th Int. Conf. on VHCF, C. Berger, H. -J. Christ (Eds. ), DVM, Berlin (2011), 121-126.

Google Scholar

[8] M. Zimmermann, A. Kolyshkin, C. Stöcker, H. -J. Christ: Characterization of the different stages of damage evolution and crack growth in pure nickel during ultrasonic fatigue, 19. European Conf. on Fracture, Kazaan, Russland, (2012), CD-ROM.

DOI: 10.4028/www.scientific.net/msf.783-786.2410

Google Scholar

[9] A. Clair, M. Foucault, O. Calonne, Y. Lacroute, L. Markey, M. Salazar, V. Vignal, E. Finot : Strain mapping near a triple junction in strained Ni-based alloy using EBSD and biaxial nanogauges, Acta Mater. 59 (2011) 3116-3123.

DOI: 10.1016/j.actamat.2011.01.051

Google Scholar

[10] C. Blochwitz, R. Richter, W. Tirschler, K. Obrtlik: The effect of local textures on microcrack propagation in fatigued f. c. c. metals, Mater. Sci. Eng. A 234-236 (1997) 563-566.

DOI: 10.1016/s0921-5093(97)00320-1

Google Scholar