In this paper, the tensile properties of dual phase (DP) steels with different martensite contents have been studied. Two steels with 0.09 and 0.15% carbon were used for the production of DP steel samples via intercritical annealing treatment, and the deformation behaviour of DP steel samples were examined during tensile loading. Although DP steels usually show two-stage work hardening behaviour, DP steels in this study with relatively high martensite content and coarse islands size exhibit a three-stage work hardening behaviour. This unusual behaviour was attributed, with the help of SEM micrographs, to decohesion of martensite-ferrite interface and martensite cracking.

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