Thickness effect on the formability of AZ31 magnesium alloy sheets

The thickness effect on formability of AZ31 magnesium alloy sheet has been widely investigated by means of uniaxial tensile tests, performed in the temperature range from 250 to 350 degrees C, with strain rates varying from 10(-4) to 10(-1) s(-1), using samples with different thickness values (from 1.5 to 3.2 mm). A preliminary microstructural study has shown that grain size and morphology are not significantly affected by both sheet thickness and heating just before the deformation step. The experimental results of tensile tests have been analysed in terms of flow curve shape, flow stress and strain to failure levels. They show that, in general, flow stress increases and ductility decreases with increasing sheet thickness even if such influence is strongly related to the temperature and strain rate conditions Finally, the analysis of the Zener-Hollomon parameter vs. peak flow stress data showed that the same mechanisms are operative in the investigated sheets.