Constant ΔΚ Fatigue Crack Growth Tests under Programmed Humidity Cycle Conditions-As a Tool to Evaluate the Effect of Humidity on Fatigue Crack Growth of Al-Li Alloys-
The effect of the relative humidity of the laboratory air on the fatigue crack growth rate in 8090 Al-Li alloys has been examined. The constant Δ<i>K</i> fatigue crack growth tests under programmed humidity cycle conditions were carried out to quantify the extent of the increase in fatigue crack growth rates due to the relative humidity. The obtained results are compared to the <i>da/dN</i>-Δ<i>K</i> relationships obtained from the constant amplitude dynamic load fatigue crack growth tests. It was found that the intrinsic fatigue crack growth rate increase with the relative humidity, but the extent of the increase was found to be considerably small compared to the growth rate difference between the laboratory air and vacuum conditions. The constant Δ<i>K</i> test at a high stress ratio under programmed humidity cycle conditions was effective for detecting the relatively small humidity effect on the fatigue crack growth rate.
- ISIJ international
ISIJ international 37(12), 1245-1250, 1997-12-15
The Iron and Steel Institute of Japan