Effects of Pre-Straining on the Behavior of Fatigue Cracks in Al 2524 T3 Alloy 2007-01-2803

The aluminum alloy 2524 was developed during the 90's mainly to be employed in aircraft fuselage panels. It is basically an improvement of the standard Al 2024 alloy, and its more rigorous processing control results in a reduced amount of impurities, especially iron and silicon. The pre-straining of aluminum alloys by stretching cold-rolled parts from their extremities is usually performed in order to obtain a more homogeneous precipitates distribution, accompanied by an increase in the yield strength. An improvement of the material's fatigue properties is also expected to occur. However, these effects can vary as the pre-straining direction is changed. The purpose of the present work is to evaluate the resistance of Al 2524 T3 sheet samples to the growth fatigue cracks having the L-T orientation. The influence of the R-ratio on the crack growth behavior is quantified by means of two-parameter modeling. Crack growth trajectory maps are then built in order to account for the pre-straining effect.