Influence of specimen width on the deformation and fracture behaviour of AA5182 sheets

• We examined the dependency of the specimen width on the tensile ductility of AA5182 sheets.
• The tensile ductility showed a maximum at a specimen width of 12.5 mm.
• During strain hardening, the alloy displayed typical serrations due to the Portevin-Le Chatelier effect.
• The results were satisfactory explained using a FE modelling based on the imperfection approach proposed by Duan et al.
• The fracture conditions were correctly captured using the Rice and Tracey criterion modified by Huang.

In this work, the influence of specimen width (in the range 6–15 mm) on the tensile deformation and fracture behaviour of AA5182 aluminium alloy sheets, characterised by the Portevin-Le Chatelier effect, was investigated. The experimental results showed that the elongation at necking and the plastic strain at fracture are influenced by the specimen geometry and, in particular, reached a maximum at a width of 12.5 mm. The experimental results are discussed on the basis of a finite element modelling of the tensile test. The material’s constitutive behaviour was implemented following an approach that accounts for microstructural inhomogeneities by considering the material to be composed of a matrix (main component) and regions of slightly higher and lower strength. The plastic properties of the three microstructural constituents were represented by interpolating the tensile stress–strain curve using Voce’s relationship. In this way, it was shown that the geometry of the specimen influences the onset and development of the stress triaxiality during plastic deformation, thus explaining the specimen width effect observed in the experimental results.