Insight into the Influence of Cu on the Corrosion Mechanism of 1%Ni Weathering Steel in a Simulated Containing NaCl Atmospheric Environment

It is difficult for traditional weathering steel (WS) to form a protective rust layer to withstand the chloride ions and high humidity. Hence, there is an urgent need to develop a new type of low-cost WS with excellent corrosion resistance in the containing NaCl environment. This study aims to determine the influence of Cu on the corrosion mechanism of 1%Ni WS in simulated containing NaCl atmospheric environments. By increasing the Cu content (0.15–0.55%), the corrosion resistance of WS is enhanced. The increasing Cu content promotes the formation of a stable and compact rust layer, significantly enriching the proportion of α-FeOOH to equip the rust layer with a physical barrier. The formation of CuO deposits in the holes and cracks make the rust layer more compact and uniform. The increased Cu content promotes the formation of CuFeO2 and increases the content of NiFe2O4. The formation of CuFeO2 and NiFe2O4 then equips the rust layer with a chemical barrier. Hence, the addition of Cu could enhance the resistance of 1%Ni WS to containing NaCl atmospheric environments.