Development of a high-alloyed duplex stainless steel with enhanced mechanical property and corrosion resistance

Artikel i vetenskaplig tidskrift, 2026

Duplex stainless steels (DSSs) are attractive structural materials because of their excellent corrosion resistance and favorable strength–ductility balance. In this study, a novel high-alloyed duplex stainless steel (HA-DSS) with a nominal composition of Fe60Cr18Co6Ni6Mo6Cu4 was developed. After solution treatment at 1180 °C, the alloy exhibited a balanced duplex microstructure with BCC and FCC phase fractions of approximately 54% and 46%, respectively. Under this condition, the alloy achieved a tensile strength of 763 MPa and an elongation of 24%. Compared with commercial 2205-DSS, the optimized HA-DSS showed significantly improved corrosion resistance. In 3.5 wt% NaCl solution, the HA-DSS exhibited a higher corrosion potential (−0.250 V vs. −0.354 V), a lower corrosion current density (0.299 μA cm⁻² vs. 0.909 μA cm⁻²), and a higher pitting potential (1.09 V vs. 1.01 V). In 10 wt% H2SO4 solution, it also showed a higher corrosion potential (−0.230 V vs. −0.269 V) and a markedly lower corrosion current density (15.33 μA cm⁻² vs. 69.99 μA cm⁻²). X-ray photoelectron spectroscopy revealed that Co, Mo, and Cu contributed synergistically to the improved passive-film characteristics. Transmission electron microscopy further showed abundant dislocations in the FCC phase and nanoscale Cu-rich precipitates in the BCC phase, which contributed to the enhanced mechanical performance. These results demonstrate that the proposed HA-DSS provides an effective strategy for simultaneously improving duplex phase stability, mechanical properties, and corrosion resistance.