Study of the correlation between pitting corrosion and the component ratio of the dual phase in duplex stainless steel welds

•The effect of the ferrite volume fraction on corrosion characteristics was investigated.•The sites of meta-stable pit were generated at lower PREN phase.•The γ2 and Cr2N seemed to serve as a path for the corrosive environment.•There is some discrepancy between the measured values(Epit) and estimated values(PREN).

Three duplex stainless steel weldments were produced by changing the chromium element to study the correlation between the pitting corrosion characteristics and the component ratio of the dual phase. The pit morphologies showed that metastable pits were generated at a lower pitting resistance equivalent number (PREN) phase. The secondary austenite phases seemed to serve as a path for the corrosive environment regardless of the ferrite number (FN). There is some discrepancy between the measured values (pitting potential (Ep) through polarization test) and expected values (sequence ranked by PREN of weaker phase) in 1 mol l−1 NaCl solution at 60 °C.