Fatigue limit in 5056 aluminum alloy extrusion studied by rotating-bending tests

Takahiro Shikama, Shinji Yoshihara, Tadashi Aiura, Dongsun Lee, Hiroshi Noguchi

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1 Citation (Scopus)


The fatigue properties of a 5056 aluminum alloy were investigated. The alloy is the most Mg-rich among commercial Al-Mg alloys and exhibits significant work hardening and strain aging. Rotation-bending tests with smooth specimen and holed specimen were performed at room temperature with stress ratio R=-1 and frequency of stress cycle F=55Hz. The experimental results show that a clear fatigue limit, as the one exhibited by steel, exists on the S-N curve of the smooth specimen. Surface observation with the replica method has revealed a wavy pattern around the second phase particle for N=106-107 but no nonpropagation crack was observed with smooth specimen. It is considered that the observed fatigue limit appeared as a result of marked work hardening and strain aging at the heavily deformed zone and fatigue cracks did not initiate from the zone up to the maximum number of stress cycle N=3.5×107 employed in the present study. On the other hand, non-propagating crack was observed with holed specimen at the stress amplitude of σa=70MPa.

Original languageEnglish
Pages (from-to)34-38
Number of pages5
JournalR and D: Research and Development Kobe Steel Engineering Reports
Issue number2
Publication statusPublished - Oct 1 2012

All Science Journal Classification (ASJC) codes

  • Mechanics of Materials
  • Metals and Alloys
  • Materials Chemistry


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