Article

Metallurgical and Materials Transactions A

, Volume 39, Issue 11, pp 2666-2680

Open Access This content is freely available online to anyone, anywhere at any time.

Effect of Frequency, Environment, and Temperature on Fatigue Behavior of E319 Cast-Aluminum Alloy: Small-Crack Propagation

  • X. ZhuAffiliated withDepartment of Materials Science and Engineering, University of Michigan Email author 
  • , J.W. JonesAffiliated withDepartment of Materials Science and Engineering, University of Michigan
  • , J.E. AllisonAffiliated withResearch & Advanced Engineering, Ford Motor Company

Abstract

The influence of test frequency on fatigue-crack propagation behavior of small cracks in E319 cast-aluminum alloy was studied using ultrasonic and conventional test techniques. It was observed that fatigue cracks grow faster at 30 Hz than at 20 kHz in air at both 20 °C and 250 °C. The effect of frequency on the fatigue-crack growth rates was attributed to an environmental effect. For E319 cast-aluminum alloy, fatigue-crack growth rate increases with increasing water exposure (characterized by the ratio of water partial pressure over test frequency, P/f), and this behavior can be estimated using a modified superposition model. The effect of temperature on fatigue-crack growth behavior was primarily attributed to the effect of temperature on Young’s modulus and yield strength. The environmental contribution to fatigue-crack growth rates modestly decreases with increasing temperature.