Université Catholique de Louvain. UCL – iMMC – IMAP

ABSTRACT:

Damage evolution in ductile metals is characterized by the nucleation, growth and coalescence of small internal voids. In aluminium alloys, the void population generally nucleates by the fracture of the iron rich intermetallic particles. Ductile failure of three 6xxx series aluminum alloys has been characterized and modelled for many hardening conditions. These alloys involve relatively similar composition and volume fraction of second phase particles. The tensile mechanical properties show the expected decrease of fracture strain with increasing strength but also major differences among the different alloys with a factor ten in terms of reduction of area at fracture between best and worst case. This can be associated to an increase of the nucleation stress when the size of the intermetallic particles decreases retarding the final fracture of the material in tension. Hence, friction stir processing has been applied to a 6056 aluminium alloy in order to assess the ability of the process to fragment the intermetallic particles, supress initial porosities and distribute them more homogeneously to aiming at improving the fracture strain of the material. Detailed microstructural analysis of the intermetallics distribution has been carried out by including 3D X-ray tomography and in-situ tensile testing in the SEM. The mechanical properties have been investigated by tensile testing under various heat treatment conditions. The seminar will finish with some perspective related to the new ERC starting grant – ALUFIX project.