The replacement of riveted joints by welding and the change-over from differential to integral structures of aluminium alloys in airframes have now become possible through the advanced laser beam and friction stir welding techniques. The change-over in the design concept is supported by the development of the new weldable alloys AA6013 and AA6056 for airframes. Possible applications are skin-stringer (T-joints) and skin-skin (butt-joints), of which the former has already been built-in in A318 and shall be introduced in the forthcoming A380 airplanes. In the present study typical features of these joints using both welding techniques are elucidated by considering mechanical properties and microstructural changes. This is necessary as temperature influence during welding and heat treatment affects the precipitation behavior of AA6013 and AA6056 alloy (AlMgSiCu alloys). Microstructural variations, hardness gradients and tensile properties of the joints are reported and referred to fatigue and fracture performance of butt-joints of airframe aluminium alloys. The results show that both laser beam and friction stir welding processes have reached a state to provide a sound quality weld. This is demonstrated by the most striking example of the conventional fatigue performance (S-N curve) of a laser beam weld which depicts good resistance to fatigue and that too in the as-welded condition without removal of surface irregularities. On the other hand, that decrease in hardness and strength (undermatching) due to the weld thermal cycle remains to be a challenge for aluminium manufacturers, since the soft zones developed may plastically deform preferentially, if design measures are not undertaken. Measures to counteract this deficiency through weld process modifications, post weld heat treatment, local engineering or through alloy modifications are required. For laser beam welding, application of new filler wires to raise the solute level for hardening and new generations of Nd-YAG laser sources to achieve narrow welds deserve consideration.


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    Titel :

    Mechanical behavior of laser beam and friction stir welded aluminium alloys for airframes


    Beteiligte:
    Vaidya, W.V. (Autor:in) / Kocak, M. (Autor:in) / Seib, E. (Autor:in) / Assler, H. (Autor:in) / Hackius, J. (Autor:in)


    Erscheinungsdatum :

    2004


    Format / Umfang :

    13 Seiten, 10 Bilder, 30 Quellen



    Medientyp :

    Aufsatz (Konferenz)


    Format :

    Print


    Sprache :

    Englisch




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