Comparative Analysis of Cast and Wrought Duplex Stainless Steels (UNS S32205 vs UNS S32750): Microstructure Evolution, Secondary Phases Precipitation and Corrosion Performance
A. Teghri, D. Hamana, S. Sehar, M. Pigato, E. Pitacco, F. Ahani, L. Chetibi, I. CalliariAbstract
Duplex stainless steels are widely employed in aggressive environments due to their unique combination of corrosion resistance and mechanical performance; however, their long-term reliability remains governed by complex interactions between alloy chemistry, manufacturing route, and secondary phase precipitation. This work provides a comprehensive comparative study of cast and wrought UNS S32205 and UNS S32750 DSSs, revealing how processing history and alloy design control microstructural evolution, precipitation mechanisms, and corrosion degradation. Thermal aging revealed a common precipitation sequence, with nitrides forming first, followed by χ and σ intermetallic phases. The refined microstructure of the wrought materials promoted faster precipitation kinetics compared with the cast counterparts. Despite their higher susceptibility to secondary phase formation, wrought super duplex 2507 exhibited enhanced corrosion stability (CPT ~76 °C) due to tungsten-induced modification of precipitation behavior and stabilization of the less detrimental χ phase.