Investigation of the Effect of Intercritical Annealing Heat Treatment Temperature on the Microstructure and Corrosion Properties of Dual-phase Steel

Dual-phase steels have many applications in various industries. By studying the various properties of these steels such as mechanical and electrochemical properties, new applications can be imagined in the use of this type of steels. Although the mechanical properties of these steels have been studied in numerous studies, the corrosion properties of Dual-phase steels need to be extensively studied. In this research, using intercritical heat treatment, the effect of heat treatment temperature on the microstructure and corrosion properties of Dual-phase steels has been investigated. For this purpose, using two methods of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), the corrosion properties of heat treated samples at 740, 770 and 800 ° C were investigated. The results showed that the martensite phase has a dual effect on the corrosion behavior of steel. On the one hand, due to the higher corrosion resistance of the martensite phase than the ferrite phase, the presence of martensite increases the corrosion resistance of steel. On the other hand, due to the potential difference between the two phases of martensite and ferrite and galvanic coupling, presence of martensite reduces corrosion resistance. The highest corrosion resistance was related to the sample prepared at 770 ° C. With increasing temperature to 800 ° C, due to the increase in the percentage of martensite phase and the intensification of the galvanic coupling between the martensite phase (cathode) and the ferrite phase (anode), the corrosion resistance of the sample decreases.