Formability extension of aerospace alloys for tube hydroforming applications

Abstract

As an essential experimental input to finite element models (FEM) of hydroforming processes, the present work focused on understanding the flow behavior of an austenitic stainless steel (SS321) during deformation. The research program also investigated the possibility of increasing the formability by using a multi-step forming process that included several cycles of forming followed by a softening heat treatment. In this context, the forming process was simplified to a tensile experiment that was divided into several deformation steps with a softening heat treatment after each forming stage. An automated deformation measurement system (ARAMIS) was used to visualize the strain distribution along the samples and to measure the maximum strain during testing. The introduction of intermediate heat treatments increases considerably the formability of SS321. These experimental data were then used to develop material models for FEM applications.