Micro-Analyses of Small Cracks in 6061-T6 Aluminium Alloy Subjected to High-Cycle Fatigue

Abstract:

The growth of a small crack controlling the high-cycle fatigue life of a precipitation-strengthened 6061-T6 aluminium alloy was critically investigated. As the applied stress lowered, the small crack was arrested for a long period (over 10⁶ cycles) at grain boundaries before regrowth, which resulted in a significantly slow growth process. The morphological and crystallographic details of the small crack were then analyzed with focused ion beam and transmission electron microscopy. It was revealed that the small crack was formed along fine persistent slip bands (PSBs) whose structure was fairly different from that reported for other metals. The concept of PSB-limited fatigue strength may be extended to include the present material type.

• Periodical: Key Engineering Materials (Volumes 525-526)
• Pages: 213-216
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.525-526.213
• Online since: November 2012
• Authors: Yoshimasa Takahashi, Takahiro Shikama, Hiroshi Noguchi
• Keywords: Aluminium Alloy, High Cycle Fatigue (HCF), Persistent Slip Band (PSB), Small Crack

References

[1] M. Goto: Fatigue Fract. Eng. Mater. Struct. Vol. 14 (1991), p.833.

[2] H. Nisitani, K. Takao: Eng. Fract. Mech. Vol. 15 (1981), p.445.

[3] C. Laird, P. Charsley, H. Mughrabi: Mater. Sci. Eng. Vol. 81 (1986), p.433.

[4] E. Hornbogen, K.H. Zum Gahr: Acta Metall. Vol. 24 (1976), p.581.

[5] H. Wu, Y. Oshida, S. Hamada, H. Noguchi: Procedia Eng. Vol. 10 (2011), p. (1973).

[6] H. Mughrabi: Int. J. Fatigue Vol. 28 (2006), p.1501.