Dependency of the mechanical properties of step quenched dual phase steels on the volume fraction of martensite

Dependency of the mechanical properties of low carbon dual phase steel on the volume fraction of martensite was evaluated for dual-phase (DP) steels processed based on the step quenching (SQ) route. It was revealed that the intercritical annealing treatment results in the disappearance of the discontinuous yielding that is characteristic for the low-carbon steels with the ferritic-pearlitic microstructures. This was related to the development of ferritic-martensitic microstructures during quenching from the intercritical annealing temperature. The hardness and ultimate tensile strength decreased with increasing holding time at the intercritical temperature and reached a plateau, which was related to the decrease in the amount of martensite during annealing. Moreover, by decreasing martensite content, the total elongation was enhanced. Accordingly, this works revealed the effects of the parameters of step quenching on the mechanical properties of DP steel

Keywords:

Dual phase steels , Martensite volume fraction , Mechanical properties