Fatigue fracture cross-sections after cyclic tests with a combination of cyclic bending and torsion of samples made of aluminum alloy 6060

The paper presents the results of fatigue tests of the 6060 aluminum alloy. The test material was taken from the profiles used for production of side windows and external doors of the passenger trains by the RAWAG company. The tests were carried out for cyclic loads with pure bending, pure torsion, and two combinations of bending and torsion. Fatigue tests were performed at zero mean values. Using scanning electron microscopy, a fractographic analysis was made, which is a supplementary basis for considerations about the mechanism of initiation and development of fatigue cracks. Based on the appearance of individual zones and the characteristics of cracks, a picture of the behavior of the material under specific conditions was obtained. Finally, the plastic property of fatigue cracks was indicated. The work demonstrates the influence of aluminum alloy processing on the fatigue properties of this alloy during operation in order to obtain maximum reliability and safety of railway transport.