Fatigue is a type of mechanical failure very common in structures. This mechanism is caused by alternating load actuation that, even if they are elastic macroscopically, leads to the initiation and eventual propagation of a crack until the collapse of the structure. For the design of structures that do not fail due to fatigue, it is essential to know the fatigue limit of the material. This property indicates that alternating tensions smaller than this value do not cause fatigue damage. The conventional methods for determining the fatigue limit include large amounts of test specimens and very long tests. Meanwhile, the thermographic method emerges, which makes it possible to obtain the fatigue limit with a small number of specimens and relatively short tests. This method would be especially convenient for aluminum alloys, since this material has very long lives, requiring even longer tests by traditional methods of determining the fatigue limit. Therefore, this project proposes to perform thermographic tests, using Risitano s method to determine the fatigue limit. In addition, as a way of checking the results obtained by thermography, a EN extrapolation is made. The first steep is obtain the EN properties of the material to calculate the alternating tension needed to generate the infinite life of aluminum. Obviously the ideal way of checking the values obtained by thermography would be from the conventional methods of determining the fatigue limit. However, the extrapolation of the EN method is a polite estimate that can be completed in a shorter time.