Effect of brief heat treatments performed between 650 and 850 °C on corrosion behaviour of a lean duplex stainless steel

• Brief-time heat treatments within 650–850 °C were performed on LDX2101®.
• The microstructural modifications due to the performed heat treatments were analysed.
• Electrochemical tests were conducted to evaluate the effect on LDX2101® corrosion resistance.
• Susceptibility to pitting and IGC strongly increased for certain time–temperature conditions.
• A correlation between microstructural modifications, Epitt. and DL-EPR test results was observed.

In this study the effect of brief heat treatments within the 650–850 °C range on pitting corrosion and intergranular corrosion resistance of a lean duplex stainless steel was investigated. Pitting potentials (Epitt.) and critical pitting temperature (CPT) were determined in sodium chloride solutions. The degree of sensitisation (DOS) to intergranular corrosion (IGC) was evaluated by DL-EPR method application. The most critical treatment conditions were observed at 650 °C and at 750 °C. A recovery of the pitting and IGC resistance of the studied lean duplex was noted at 850 °C due to the redistribution of chromium towards the depleted zones.