EXPERIMENTAL EVALUATION OF FATIGUE PROPERTIES OF WROUGHT AL ALLOYS EN AW-6082 AND EN AW-7075

The paper summarizes experimental results of measurements of basic fatigue properties of two aluminium alloys (EN AW-6082/T6 and EN AW-7075/T6) which were produced by technology of hot extrusion. Materials produced by this technology display a visible directionality of the structure in consequence of the used manufacturing and so varied mechanical characteristics in different directions should be supposed. Fractographic analysis of fatigue crack propagation characteristics implies significant local difference too. After processing of rather extensive set of experimental results (which were acquired mostly at bending type of fatigue loading), it is however possible to identify only nonsignificant influence of this structure directionality on position of S-N dependences at monitored aluminium alloys. Consequently the microstructural dissimilarities have no fundamental influence on fatigue properties in global look (at flexural loading). Basic possibilities of application of selected non-destructive testing methods for more exact identification of different stages of fatigue process directly during cyclic loading are briefly presented at the second part of the contribution. The main attention is targeted on more accurate identification of the first stage of fatigue cracks propagation. The procedure making use of acoustic emission method is described there.