Study of Corrosion Behavior in Resistance Spot Welds of Thin Sheets of Zinc-Coated Interstitial-Free Steel

The aim of this research is to investigate the corrosion behavior of the resistance spot-welded joints of the zinc-coated interstitial free steel (IF steel) in contrast to the steel. For this purpose, the corrosion behavior of the welds and base interstitial-free steel (IF steel) was investigated in two solutions including 0.1 M NaCl + 0.1 M NaOH and 0.1 M NaCl + 0.1 M H2SO4. Potentiodynamic polarization curves and electrochemical impedance spectroscopy test results showed that the corrosion resistance of the base metal and welds in 0.1 M NaCl + 0.1 M NaOH solution is higher than their corrosion resistance in 0.1 M NaCl + 0.1 M H2SO4 solution. It was found that the corrosion resistance of the IF steel base metal in both solutions is higher than that of the welds obtained by the steel. According to the cyclic polarization curves, it can be said that the passive film formed on the specimens in 0.1 M NaCl + 0.1 M NaOH solution is highly susceptible to pitting corrosion while the specimens do not show any passivation behavior in 0.1 M NaCl + 0.1 M H2SO4 solution and undergo severe uniform corrosion.

Automated summary

The research revealed that the corrosion resistance of the welds obtained by the steel is lower than that of the base metal of IF steel, and the corrosion resistance of the base metal of IF steel is higher than that of the welds in both solutions.