Processing Route Effects on the Mechanical and Corrosion Properties of Dual Phase Steel

Processing Route Effects on the Mechanical and Corrosion Properties of Dual Phase Steel

The mechanical and corrosion behaviors of low carbon DP steel were studied based on different processing routes: (1)intercritical annealing (IA), (2) step quenching (SQ) via austenitization and quick transferring of the sample to the secondfurnace, and (3) Slow SQ via furnace cooling to the desired temperature. The properties were found to be highly dependenton the volume fraction of martensite (VM) and the density of ferrite/martensite interfaces. However, at the same martensitecontent, the mechanical properties of Slow SQ sheet were inferior than those of SQ and IA sheets, which were related to therelatively poor work-hardening behavior due to the severe partitioning of Mn between ferrite and martensite phases. Thelatter was also responsible for an increase in the corrosion current density (icorr) via galvanic corrosion. These results wereanalyzed based on the polarization curves and Nyquist plots obtained from the electrochemical impedance spectroscopytest. This study revealed that the SQ route can result in both better mechanical performance and higher corrosion resistance.

The mechanical and corrosion behaviors of low carbon DP steel were studied based on different processing routes: (1)intercritical annealing (IA), (2) step quenching (SQ) via austenitization and quick transferring of the sample to the secondfurnace, and (3) Slow SQ via furnace cooling to the desired temperature. The properties were found to be highly dependenton the volume fraction of martensite (VM) and the density of ferrite/martensite interfaces. However, at the same martensitecontent, the mechanical properties of Slow SQ sheet were inferior than those of SQ and IA sheets, which were related to therelatively poor work-hardening behavior due to the severe partitioning of Mn between ferrite and martensite phases. Thelatter was also responsible for an increase in the corrosion current density (icorr) via galvanic corrosion. These results wereanalyzed based on the polarization curves and Nyquist plots obtained from the electrochemical impedance spectroscopytest. This study revealed that the SQ route can result in both better mechanical performance and higher corrosion resistance.