Formability of cryo-rolled aluminium in uniaxial and biaxial tension

Pure aluminium sheets have been processed by cryo-rolling followed by recovery annealing in order to refine the microstructure. Tensile testing revealed that these materials have low uniform elongations but high reduction in area at the fracture surface. Measurement of the full forming limit diagram has shown that although the strain to failure in uniaxial tension is poor, strain in biaxial stretching was relatively good, having a forming limit strain >20%. We have therefore demonstrated that although this fine grained material may exhibit poor formability in tension, in other strain paths such as biaxial stretching it shows forming limits that may be sufficient for manufacture in some forming processes.