This work examined the effect of multiaxial stress on deformation characteristics of a superplastic aluminum alloy 8090 by deforming the sheet into a die with a cylindrical cavity. Several interrupted tests were performed to bulge the sheets to various de This work examined the effect of multiaxial stress on deformation characteristics of a superplastic aluminum alloy 8090 by deforming the sheet into a die with a cylindrical cavity. Several interrupted tests were performed to bulge the sheets to various de