<p>This study examined corrosion behavior and resistance mechanisms of Q235 carbon steel, galvanized Q235 steel, brass, and 5A06 aluminum alloy in high-chloride coastal environments via neutral salt spray testing, ranking their corrosion resistance from highest to lowest as 5A06 aluminum alloy, brass, Q235 steel, and galvanized Q235 steel. 5A06 superiority stems from stable Al₂O₃ passive film—an effective protective barrier with partial self-repair capability under chloride-containing conditions; brass initially showed good corrosion resistance but suffered galvanic corrosion between copper and zinc phases after prolonged exposure, leading to gradual degradation; Q235 steel experienced severe corrosion with cracks and perforations that accelerated structural deterioration, and its porous, non-adherent corrosion products provided no protection; galvanized Q235 steel initially gained cathodic protection from zinc coating (acting as a sacrificial anode) to delay substrate corrosion, but zinc layer was gradually consumed over time, and once depleted, steel substrate corroded rapidly, making it the least resistant.</p>