Shear test-based identification of hardening behaviour of stainless steel sheet after onset of necking

In the metal sheet-forming process, localised thinning immediately before failure is a rapid and intensive process. This paper discusses such intensive thinning and elaborates on the importance of the hardening behaviour at large plastic strains. In particular, for the reliable prediction of intensive sheet-thinning evolution, an accurate determination of the hardening behaviour is important; however, the identification cannot be performed using classical uniaxial tests owing to necking. Therefore, this paper describes the development of a new shear specimen that provides enough data for hardening curve characterisation up to an equivalent plastic strain value that is twice that in a tensile test. After characterisation, based on the inverse identification procedure, two verification cases confirmed the identified data. Both cases are typically considered stochastic processes, and they exhibit a large scatter in the experimental testing: Necking evolution in a uniaxial case and localisation evolution of a notched specimen. However, the verification analyses confirm that both processes are deterministic, and a good prediction could be reached exclusively by a precise identification of the hardening behaviour at large plastic strains.