Abstract
Super austenitic stainless steels (SASS) face challenges like galvanic corrosion and antibacterial performance when welded to carbon steel (Q235) in marine environments. This study demonstrates that adding 1.0 wt% cerium (Ce) to SASS refines the heat-affected zone (HAZ) grain structure (from 7 μm to 2 μm), suppresses detrimental σ-phase precipitation, and forms a dense oxide film. Electrochemical analyses confirmed this optimized composition increases charge-transfer resistance (to 2.2 × 10(3) Ω cm(2)) and reduces passivation current density (to 0.12 μA/cm(2)), significantly enhancing corrosion resistance. Additionally, 1.0 wt% Ce disrupts sulfate-reducing bacteria (SRB) membranes, reducing survival to <1%. However, excess Ce (≥1.5 wt%) forms coarse CeO(2) particles, accelerating corrosion via porous films and micro-galvanic coupling. These findings provide a practical strategy for designing corrosion-resistant, antimicrobial welded joints in marine infrastructure.