Improved rule of mixture for determination of mechanical properties of dual phase steel with different martensite fraction

Dual phase (DP) steels are widely used materials for sheet metal applications for example in the automotive industry. They combine high strength with good ductility. Their microstructure contains two phases: soft and ductile ferrite as well as hard and brittle martensite. Depending on the heat treatment the martensite content varies. This offers the adjustment of material properties either for the whole sheet during the production process or locally by applying inductive heating and gas cooling before or after the forming process. This local treatment could be used at joints for example.