Abstract
In this work, different dual phase (DP) microstructures were produced in 15CrNiMo7 steel, in order to study the effect of martensite volume fraction (MVF), martensite morphology (MM), and epitaxial ferrite (EF) on tensile strength behavior. Mechanical properties of five different DP steels have been investigated by carrying out tensile and hardness tests. By increasing the martensite content, both tensile and yield strengths increased. The presence of new ferrite caused a decrease in strength and increase in ductility. Fractography analysis after the tensile test was performed by using SEM.

Key words
high martensite, morphology, epitaxial ferrite, tensile strength, dual-phase steel

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