In the course of steel development, heterogeneity at various scales has been elaborately controlled in order to realize superior characteristics at macro scale. Since the development of sheet steels for automotive parts shifted its focus from ferritic mild steels to complex high and ultra-high strength steels, the steel industry has required more powerful tools for both the precise analysis of macroscopic behaviour and the development of new materials. In this context, numerical simulations with advanced constitutive modelling have played important roles in forming and crash applications.

Firstly, the relationship between the work hardening behaviour at large strains and the evolution of microstructure will be discussed based on the simple shear experiments of ferritic single crystals and crystal plasticity analysis. TEM observations have been performed to study microstructures after shear deformation. The work hardening behaviour depends largely on the crystal orientation, which could be correlated to the type of microstructure via the activity of slip systems.

Secondly, fracture behaviour of dual phase steel has been investigated by in-situ tensile tests and finite element simulations. The experiments have shown that the damage is dominated by fracture of the martensite islands and decohesion at the martensite/ferrite interfaces. The FE simulations have shown that the martensite fracture and the interface decohesion have a significant influence on the stress and strain partitioning between the two phases.

Effectiveness of the combination of advanced engineering and scientific approaches for industrial applications of sheet steels will be discussed.