Superplastic forming of 7475 Al alloy by variable-pressure blowing

The superplastic forming characteristics of 7475 Al alloy were studied using the constant-pressure, constant strain rate, two-step and three-step variable-pressure forming methods. The step-change variable pressure forming processes which involve steps of isobaric forming with the strain rates kept within the superplastic region not only shortened the forming time spans for specific amount deformation, but also resulted in satisfactory thickness profile.