Acoustic emission (AE) technique is commonly applied in different materials in order to evaluate their internal fracturing condition in real time. Apart from the number of acquired signals, which are correlated to the number of active cracking sources, qualitative features of the acoustic waveforms shed light in the dominant fracturing mode. This is due to the fact that the emitted waves depend on the relative motion of the crack sides at each incident. The fracture process of most engineering materials includes shift between modes and therefore, non-invasive and real time characterization of the dominant mode supplies information on the current condition as well as poses an early warning before final failure. Although a lot of work has been done on acoustic emission characterization of fatigue damage, the work on welded components is scarse. In the present study aluminum plates are cross-welded and loaded until fracture in tension-tension fatigue experiments at different load levels. Their full acoustic activity is recorded by four sensors along with all mechanical parameters. It is shown that study of the acoustic emission rate relatively to the applied load, and qualitative waveform parameters like the frequency content and duration can be used to study the evolution of the crack under the different modes.