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.