PSI - Issue 13

Yoshimasa Takahashi et al. / Procedia Structural Integrity 13 (2018) 1010–1013 Author name / Structural Integrity Procedia 00 (2018) 000 – 000

1013

4

(a)

(b)

(c)

50  m Ambient air (110 MPa)

50  m

50  m

Dry air (97.5 MPa)

N 2 (85 MPa)

Fig. 5. Micrographs showing small fatigue crack growth behavior during  a step-up tests.

4. Summary

In this study, the fatigue properties of a new Al alloy (6061-T6 plus 0.5wt% solute Mg) is investigated in different environments (ambient air, dry air, dry nitrogen). The S - N curve of the alloy shows a clear knee-point (fatigue limit), and it is shown to be controlled by the threshold against small crack propagation regardless of the environment. On the other hand, the coaxing effect of pre-fatigued specimen (i.e. containing a non-propagating crack) is clearly observed in the ambient air where the small crack growth tends to be mode I in character.

Acknowledgements

This study was supported in part by the Kansai University Grant-in-Aid for progress of research in graduate course (2017) and also by the Kansai University Fund for Supporting Young Scholars (2017).

References

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