Formability of thin stainless steel bipolar plates for hydrogen fuel cells considering grained anisotropy

This study presents a combined numerical and experimental investigation into the formability of thin super ferritic and austenitic stainless steel bipolar plates for hydrogen fuel cell. A finite element framework incorporating grained anisotropy is developed using a Voronoi tessellation-based approach in Abaqus/Explicit, where individual grains are randomly assigned true stress-strain curves derived from tensile tests to replicate the heterogeneous deformation behaviour of polycrystalline materials. Micro stamping simulations capture the evolution of equivalent stress, plastic strain, and thickness distribution across the formed micro-channel geometries. Corresponding stamping experiments are conducted on approximately 0.1 mm thick stainless steel sheets. The measured local thinning, channel depth, and overall geometry are used to validate the numerical predictions. Comparative analysis reveals that the super ferritic stainless steel exhibits lower ductility and greater sensitivity to geometric constraints. In contrast, the austenitic grade shows higher formability and more uniform material flow, resulting in reduced localised thinning and improved shape accuracy. The Voronoi-based model accurately predicts critical deformation characteristics for both alloys, supporting process design and optimisation to enhance the quality and reliability of bipolar plates. This work advances the understanding of microforming behaviour and provides practical insights for manufacturing hydrogen fuel cell components.