Investigation on Fatigue Crack Interaction with Grain Orientation during TMF Tests in Nickel-Base Superalloy

Abstract:

Turbine discs in the gas turbine engine experience a wide range of stress and temperature during service. These result in distinct deformation mechanisms characteristic of different temperatures and stresses, and the cumulative effect of these on fatigue life is of much interest as turbines run hotter and thermal stresses rise. Thermo-mechanical fatigue tests are used to investigate performance at specific disc locations and have been performed on the alloy RR1000, a nickel based superalloy. This work describes a series of examinations to explore the interaction between temperature-loading conditions, deformation and failure mechanisms of an out-of-phase, largely compressive, thermo-mechanical cycle. Fatigue cracks initiated in the corners of the rectangular-sectioned test pieces and propagated to form approximately quarter-circle cracks. The interaction of the microstructure and deformation mechanism with the crack growth path has been investigated using Electron Backscatter Diffraction (EBSD) analysis complemented by Transmission Electron Microscopy (TEM) of specimens sampled from specific locations in the vicinity of a secondary crack.

• Periodical: Advanced Materials Research (Volumes 891-892)
• Pages: 1289-1294
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.891-892.1289
• Online since: March 2014
• Authors: Olivier M.D.M. Messé*, Svjetlana Stekovic, Mark Hardy, Cathie M.F. Rae
• Keywords: EBSD, Fatigue Crack Propagation, Nickel-Based Superalloy, RR1000, Slip Traces Analysis, TMF

References

[1] M.D. Sangid, T. Ezaz, H. Sehitoglu, and I.M. Robertson. Energy of slip transmission and nucleation at grain boundaries. Acta Materialia, 59(1): 283–296, (2011).

DOI: 10.1016/j.actamat.2010.09.032

[2] L. -Q. Chen. Phase-field models for microstructure evolution. Annual Review of Materials Science, 32: 113–140, (2002).

[3] V.A. Vorontsov, C. Shen, Y. Wang, D. Dye, and C.M.F. Rae. Shearing of γ' precipitates by a 112 dislocation ribbons in Ni-base superalloys: A phase field approach. Acta Materialia, 58(12): 4110 – 4119, (2010).

DOI: 10.1016/j.actamat.2010.03.041

[4] L. Kovarik, R.R. Unocic, J. Li, and M.J. Mills. The intermediate temperature deformation of Ni-based superalloys : Importance of reordering. The Journal of The Minerals, Metals & Materials Society, 61(2): 42–48, (2009).

DOI: 10.1007/s11837-009-0026-6

[5] D. Child, G. West, and R. Thomson. Assessment of surface hardening effects from shot peening on a Ni-based alloy using electron backscatter diffraction techniques. Acta Materialia, 59(12): 4825–4834, (2011).

DOI: 10.1016/j.actamat.2011.04.025