Characterization of laser and electron beam welded Al alloys. Charakterisierung von laser- und elektronenstrahlgeschweissten Aluminiumlegierungen

Electron beam, CO_2, and Nd:YAG laser beam welding were performed on four different aluminium alloys, namely alloys 5005, 2024, 6061, and 7020. The plate thickness was 5 mm except alloy 5005 which was 3 mm thick in all cases and Nd:YAG laser beam welding was performed on 3 mm thick plates for all four alloys. Microstructural characterization of the weld metals was made by optical and scanning electron microscopies. A very low level of porosity was observed in all EB welds due to surface cleaning prior to welding and the vacuum environment of the EB welding process. In the case of CO_2 laser beam welding, high porosity level was observed. The pores observed in laser beam welded joints were varied small to large in size. Furthermore, the loss of Mg apparently took place in electron beam welding of all the alloys, which leads to the loss of strength in fusion zone (strength undermatching). The use of filler wire in laser beam welding processes improved the base metal property (strength) degregation to some extent in some cases. However, the strength undermatching was still to be observed in almost all of the cases. (orig.)Also published in: Prakt. Metallogr. 36(1999)2SIGLEAvailable from TIB Hannover: RA3251(2000/9) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman