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

Characterisation of electron beam welded aluminium alloys

Electron beam (EB) welding was performed on three different aluminium alloys, namely alloys 2024, 5005, and 6061 (plate thickness 5 mm except alloy 5005 which was 3 mm in thickness), to establish the local microstructure-property relationships that would satisfy the service requirements for an electron beam welded aluminium alloy component with weld zone strength undermatching. Microstructural characterisation of the weld metals was carried out by optical and scanning electron microscopy. A very low level of porosity was observed in all EB welds owing to surface cleaning before welding and the vacuum environment of the EB welding process. Extensive microhardness measurements were also conducted in the weld regions of the joints. Global tensile properties and fracture toughness properties (in terms of crack tip opening displacement, CTOD) of the EB joints were determined at room temperature. The effects of strength mismatch and local microstructure on fracture toughness of the EB joints are discussed. The purpose of the present paper is to report the partial results of the European Brite-Euram project ASPOW (assessment of quality of power beam weld joints; BRPR-CT95-0021), which has been undertaken predominantly by industrial companies to establish a European framework for destructive and non-destructive testing and assessment criteria for laser and electron beam welds of over 20 metallic materials. (orig.)Also published in: Science and Technology of Welding and Joining, v. 4(1990), no. 5, p. 317-323Available from TIB Hannover: RA 3251(2001/1) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Pulmonary rehabilitation for COPD

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