Mechanical and corrosion behavior of plain low carbon dual-phase steels

Dual-phase steels are being used in automobile industries for last three decades. The mechanical properties of dual-phase steels can be altered by varying its martensite volume fraction. However, the benefits obtained in mechanical properties have to be viewed in light of other properties such as corrosion resistance. In this work, dual-phase steels with different volume fractions of martensite are obtained after thermal processing using different intercritical soaking times. The mechanical properties of dual-phase steels such as Vickers hardness and tensile properties are measured. Corrosion properties are evaluated using potentiodynamic polarization test and immersion test. It was observed that the tensile strength and hardness increased and ductility decreased with increase in martensite volume fraction. The corrosion rate for dual-phase steels is found to be lower than that for subcritically heat treated ferrite–pearlite steel. The higher corrosion resistance of dual-phase steels is explained on the basis of microstructural features.