Corrosion Behavior of Ni, Cr-Containing Corrosion Resistant Steel in High Temperature and High Cl^- Environment

Steels containing Ni and Ni-Cr were smelted, and the corrosion behavior of these steels in tropical marine atmosphere was studied by outdoor exposure test combined with rust layer composition analysis and corrosion rate calculation. The results showed that the corrosion rates of plain carbon steel, Ni-containing steel, and Ni-Cr-containing steel in the experimental environment were 66.84, 41.54, and 38.29 μm/a, respectively. Alloying elements Ni and Cr significantly improved the corrosion resistance of steel. The rust layer on the surface of samples was mainly composed of γ-FeOOH and α-FeOOH, and also contained relatively small Fe₃O₄ particles and FeO lamellae. The rust layer of ordinary carbon steel was thicker than that of the other two steels, and the content of α-FeOOH in the rust layer of carbon steel was higher and more stable, while the samples with Ni and Ni-Cr had no stable rust layer formed on the surface after half a year of testing. After half a year of outdoor exposure test, the content of Ni element in the rust layer was small, but there was an enrichment phenomenon in the steel under the rust layer. Cr and Cu were enriched in pitting pits.