Enhanced mechanical properties of dual-phase steel by repetitive intercritical annealing

The effect of repetitive intercritical annealing on the mechanical properties and work-hardening response of a typical C–Mn dual-phase (DP) steel was studied by consideration of different pre-intercritical annealing microstructures and martensite volume fractions. It was revealed that the DP steels produced from the initial martensitic microstructure have much better mechanical properties compared with those originated from the ferritic–pearlitic banded microstructure. The repetitive intercritical annealing of the initial martensitic microstructure was effective for the enhancement of strength–ductility balance, where at a comparable ductility; a twofold increase in the tensile strength was obtained. Finally, these results were discussed based on the Crussard–Jaoul work-hardening rate analysis.