5th International High Manganese Steel Conference - HMNS 2022

The global formability of sheet materials corresponds to the ability to undergo uniform plastic deformation without the formation of a localized neck, whereas the local formability addresses the ability to undergo plastic deformation in a local area without fracture. Both the local and the global formability are therefore important properties that can become limiting factors for the application of medium manganese steel in the automotive industry. While for the stretch formability and drawability, the global formability is of critical importance, in particular the edge crack resistance relates to the local formability. In our contribution, we aim to present a damage mechanics based approach to evaluate the local and the global formability of medium manganese steel. For the characterization of local formability, our approach considers strain-based, state-of-stress dependent criteria for damage initiation and ductile fracture. It belongs to the group of phenomenological, coupled damage mechanics models which take damage-induced softening effects into account. On the other hand, the modified maximum force criterion is applied to predict the localization resistance. After introducing the simulation framework, we will develop material parameter identification strategies, show validation examples, and compare the localization, damage and fracture properties of a medium manganese steel to a conventional dualphase steel of grade DP1000. These studies will reveal significant differences between the two materials and allow to give requirements for future materials design.