M–K Ductile Damage Theory Predicts Formability of Stainless Steel Ultra-Thin Strips in Stamping

To address the difficulty in forming ultra-thin stainless steel strips, this study focuses on 304 stainless steel ultra-thin strips. By conducting tension and forming limit experiments, the basic mechanical properties and FLC (Forming Limit Curve) of the material are determined, and its formability is systematically investigated. Additionally, to improve testing efficiency and reduce resource consumption, this paper predicts the FLC forming curve of the ultra-thin strip based on the M–K ductile damage model, which is then validated against experimental results, establishing a reliable FLC prediction model. Moreover, to relate it to practical industrial production applications, this study simulates the stamping process of box-shaped components made from the ultra-thin strip based on the theoretical model, exploring the influencing factors of stamping processes on the formability of the ultra-thin strip. The research findings indicate that among the hard, semi-hard, and soft stainless steel ultra-thin strips, the soft one exhibits the best formability, and the 0.05 mm thickness is less formable compared to the 0.1 mm strip. The simulation results demonstrate that the M–K ductile damage theory can reasonably predict the formability of the ultra-thin strip. Furthermore, optimizing the chamfer size in the stamping process, reducing the friction coefficient between the die and the ultra-thin strip, and lowering the stamping speed effectively improve the formability of the ultra-thin strip.