High strength sheet steels, such as advanced high strength steels (AHSS), are fundamental for the lightweight design of structural components in sectors like the automotive. Thanks to their excellent combination of strength and ductility, these high-performance materials allow to reduce part weight by sheet downgauging, while maintaining or even improving crash safety.

However, they have also introduced new challenges related to their higher cracking susceptibility during cold forming or under impact loading. In this context, concepts like cracking resistance, damage tolerance or fracture toughness have become unavoidable when addressing the design and application of high strength steels.

In this talk, the importance of implementing new fracture mechanics-based criteria to understand the cracking behaviour and in-service performance of high strength sheet materials will be shown. This behaviour can be addressed by understanding their fracture toughness properties. Accordingly, fracture toughness can be used to address many issues related to the cold formability of high strength steels and predict their fracture behaviour in different forming operations such as stamping, punching, hemming, deep drawing or high demanding bending.

The talk is divided into three presentations. The first one, given by Dr. Casellas, will provide the context to understand the need of new fracture criteria for AHSS, including relevant research findings and noteworthy previous projects. The second one will be presented by Dr. Frómeta, who will talk about the RFCS (EU Research Program) ToughSteel initiative and will present novel testing methodologies and successful industrial application cases. Finally, Javier Lopez-Quiles, will give some insights about the current state and the next steps on the standardization of the new fracture toughness testing methodologies for high strength ductile metal sheets.