Integration of Local Formability Limits of AHSS into Local/Global Formability Map

In accordance with the emergence of new automotive steel types, such as 3rd Generation advanced high strength steel, the reasonable estimation of their local ductility (tight-radius bendability, edge stretchability, etc.) has become of great importance to the automobile industry. Regarding this, the local/global formability map, expressed by true fracture (or thickness) strain and uniform strain, has recently been introduced to present intrinsic local and global formability of steels simultaneously. In this study, an improved form of the local/global formability map is proposed in combination with limit strain models. Isolines of tight-radius bending limit and hole expansion ratio at arbitrary intervals are superimposed on the existing map, thereby enabling designers of stamping parts to easily confirm whether their material selections are appropriate for concerned part geometries, or vice versa.