Study on the Stabilization Technology of Rust Layer on Q420qNH Weathering Steel Surface Under a Simulated Marine environment

This study adopts a stabilization treatment agent of CuSO4, FeSO4, NaHSO3, NaCl, and CaCl2 solution systems to stabilize the treatment of Q420qNH weathering steel (WS) surfaces. Comparative analysis was conducted between WS with (sample A) and without (sample B) stabilization treatment. The investigation included dry/wet cyclic corrosion tests, electrochemical techniques, morphological characterizations, and component analyses. The findings indicate that sample A exhibits greater corrosion weight gain and rust layer thickness than sample B. The rust layer of sample A, characterized by higher density and flatness, predominantly consists of Fe3O4, gamma-Fe2O3, alpha-FeOOH, gamma-FeOOH, beta-FeOOH, and CaSO4 phases. CaSO4 notably contributes to filling the defect in the rust layer, thereby improving the structure of the initial layer. After 64 cycles of the corrosion test, sample A's rust layer appeared uniform and continuous, with a 27% alpha-FeOOH content (a 7% improvement) and a self-corrosion potential (E-corr) of -0.681 V, an improvement of 120 mV. Surface stabilization treatment was observed to promote the enrichment of alloying elements such as Cu and Cr in the rust layer's cracks, thus accelerating the formation of a dense, stable rust layer and substantially enhancing the corrosion resistance of rust layer on Q420qNH WS surface.