Characterisation of electron beam welded aluminium alloys

Abstract

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.