Effect of Humidity on Fatigue Strength of Age-Hardened Al Alloy

Abstract:

Ultrasonic and rotating bending fatigue tests were carried out using plain specimens and specimens with a small blind hole for an extruded and age-hardened Al alloy 7075-T6 in different environments in order to investigate the effect of humidity on fatigue strength and fracture mechanism. Fatigue strength was decreased by high humidity under both tests. The effect of humidity on fatigue strength was larger in ultrasonic fatigue. The humidity affected both of crack initiation and propagation processes. Crack propagated in tensile mode then changed to shear mode macroscopically in all environments under ultrasonic fatigue, though it was only in tensile mode under rotating bending fatigue. These differences in fracture mechanism related to the difference in environmental effect on fatigue strength in both tests.

• Periodical: Key Engineering Materials (Volumes 417-418)
• Pages: 373-376
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.417-418.373
• Online since: October 2009
• Authors: T. Fukudome, Norio Kawagoishi, K. Kariya
• Keywords: Aluminium Alloy, Fatigue, Fracture Mechanic, Humidity, Rotating Bending, Ultrasonic

References

[1] T. Broom and A. Nicholson, Journal of the Institute of Metals, Vol. 89 (1961), p.183.

[2] Haftirman, S. Hattori and T. Okada, Trans. Japan Soc. Mech. Eng., Vol. 62 (1996), p.1140.

[3] N. Kawagoishi, M. Oki, M. Goto, Q. Chen and Q.Y. Wang, Trans. Japan Soc. Mech. Eng., Vol. 72 (2006), p.1356.

[4] R.E. Ricker and D.J. Duqette, Metallurgical Transactions, Vol. 19A (1988).

[10] [4] [10] [5] [10] [6] [10] [7] [10] [8] [10] [9] [0] [50] 100 150 200 250 300 350 Stress amplitude, σσσσa (MPa) %umber of cycles to failure, �f (cycle) Drilled specimen In air In high humidity Plain specimen In air In high humidity σa = 270MPa, 2. 10×105 σa = 221MPa, 9. 75×104 σa = 190MPa, 2. 62×105 σa = 270MPa, 8. 4×104.

DOI: 10.3389/fmicb.2019.02070