Fatigue Properties and Fracture Characteristics of the Aluminum Alloys for High-Speed Train Carbody
The fatigue tests on two types of domestic aluminum alloys were conducted and the P-S-N curves of both aluminum alloys were obtained. The microscopic characteristics at the fatigue fracture surface were observed with scanning electron microscopy. The results show that the tensile strength of A7 is 376MPa, while the tensile strength of A6 is 311MPa. The fatigue strength of A7 is 75MPa at 107 circles, and it is just a little higher than that of A6, which is 71.57MPa. The fatigue cracks initiated from or near the surface of the specimen. The fatigue fracture can be divided into three parts, namely, the initiation zone, the propagation zone and the sudden fracture zone. Typical characteristics could be observed on fracture surface.A6 has better plasticity than A7.