Low cycle fatigue damage mechanism of the lightweight alloy Al2024

Detection of cracks in Al2024 T351 specimens subjected to low cycle fatigue loading by a certain non-destructive inspection technique is demonstrated. In the experimental phase of the study, notched round specimens were fatigue loaded. The tests were performed at different constant strain amplitudes at room temperature. For identifying the crack initiation loci, the specimens were removed from the testing machine after a certain number of cycles and were non-destructively inspected via X-ray technique. Pictures were taken successively while incrementally turning the sample. The re-constructed data were visualized via software (VGStudio MAX 2.1) to obtain a 3D image of the specimen, showing all the details of its inner structure. By taking “virtual” slices from the data, quantification of microstructural properties was done using classical methods. This allowed verifying some frequently mentioned statements concerning the low cycle fatigue behavior of high-strength aluminum alloys. Furthermore, new findings related to the tri-axiality dependence on the resulting fracture process and those related to damage initiation caused by decohesion were also discovered.

► High resolution synchrotron X-ray measurements for LCF analyses of Al2024.
► For monotonic loading crack initiation in the interior, for cyclic loading surface cracks.
► Dependence of tri-axiality on crack initiation and propagation.