Combined mechanics-materials based optimization of superplastic forming of magnesium AZ31 alloy

A new optimization approach for superplastic forming of Mg AZ31 alloy is presented and experimentally validated. The proposed new optimization approach is based on a multiscale failure criterion that takes into account both geometrical necking and microstructural evolution, yielding a variable strain rate forming path instead of the commonly used constant strain rate approach. Uniaxial tensile tests and free bulge forming experiments, in conjunction with finite element analysis, are used to evaluate the proposed optimization approach. Significant reduction in forming time is achieved when following the proposed optimization approach, without compromising the uniformity of deformation.