Electrochemical Properties of UNS S 32750 and UNS S 32760 Annealed Super Duplex Stainless Steels

Abstract

Super duplex stainless steels (SDSSs) exhibit high pitting corrosion resistance in seawater because of their dual-phase composition of austenite and ferrite, requiring solution annealing. Therefore, the solution annealing (1100 °C) of SDSS is a crucial step to optimize the corrosion resistance of stainless steel during the manufacturing process. UNS S 32760 is an SDSS formed by adding 0.6 wt.% W and 0.7 wt.% Cu to UNS S 32750. The change in the chemical compositions of the alloys alters the solution annealing temperature. This study electrochemically analyzed the effects of the addition of Cu and W on the solution annealing of SDSS. UNS S 32750 and UNS S 32760 exhibited the most favorable electrochemical properties at 1100 and 1080 °C, respectively, owing to their chemical compositions. UNS S 32750 exhibited high pitting corrosion resistance, whereas UNS S 32760 exhibited highly uniform corrosion resistance.