Praezisionsbearbeitung mit Festkoerperlasern: Fuegen. Teilprojekt: Schweissen von Werkstoffen bzw. Werkstoffkombinationen mit geringer Schweissneigung Abschlussbericht

The aim of this project was to evaluate the weldability of materials which are difficult to joint by conventional methods using a pulsed Nd:YAG laser. Because high strength aluminium alloys found increased interest for applications in the automobile and aircraft industry the research was focussed on the welding of the age hardenable alloys AlMgSi1, AlCuMg1 and AlZnMgCu1,5. Welding was conducted with and without filter. Only for the alloy AlZnMgCu1,5 the use of a filler was essential to achieve a good joint. The tensile strength of AlMgSi1 joints reached 64% of the value for the base material thus exceeding the tensile strength of TIG- and WIG-welded joints. With a subsequent heat treatment (solutionizing and age hardening) the tensile strength was increased up to 71%. For the alloy AlCuMg1 values of 61 and 86% respectively were achieved. Welding with filler led to a further increase of the tensile strength (approximately 10% compared to the values of joints welded without filler). For AlMgSi1 an AlSi12 filler was best whereas for AlCuMg1 and AlZnMgCu1,5 the addition of AlMg5 led to better results. The fatigue strength of AlMgSi1 and AlCuMg1 joints drops to values 40 to 60% below those of the base material. Considering that the joints were tested in the as-welded condition this decrease is not dramatical. Moreover, the variance is low. However, the AlZnMgCu1,5 joints were notch-sensitive and due to an extreme variance no Woehler curve could be determined. Therefore Nd:YAG laser welded joints of this alloy cannot be recommended for applications were fatigue resistance is required. (orig.)SIGLEAvailable from TIB Hannover: F99B841+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman