Corrosion Behaviors of Carbon Steel and Ni-Advanced Weathering Steel Exposed to Tropical Marine Atmosphere Yueming Fan, Wei Liu, Zongteng Sun, Thee Chowwanonthapunya, Yonggang Zhao, Baojun Dong, Tianyi Zhang, Wongpat Banthukul, and Xiaogang Li (Submitted June 30, 2020; in revised form August 27, 2020; Accepted: 12 September 2020) The corrosion behaviors of carbon steel and Ni-advanced weathering steel exposed to tropical marine atmosphere were investigated by using electrochemical impedance spectroscopy, x-ray diffraction, trans- mission electron microscope and x-ray photoelectron spectroscopy measurements. The results showed that Ni had almost no effect on corrosion kinetics and electrochemical performance of Ni-advanced weathering steel in mild atmosphere. Conversely, Ni-advanced weathering steel in marine atmosphere showed a sig- nificant superiority in improving corrosion resistance compared with carbon steel. Moreover, the mass formation of NiFe 2 O 4 in the inner rust layer promoted the stability of the corrosion resistance improvement rate of Ni-advanced weathering steel with the increase in exposure time. Therefore, Ni-advanced weath- ering steel seemed to be more suitable for the harsh marine atmospheric environment. Keywords corrosion behavior, Ni-advanced weathering steel, rust layer, tropical marine atmosphere 1. Introduction It is well known that the addition of a small amount of alloying element Ni to weathering steel can significantly enhance its resistance to marine atmospheric corrosion (Ref 1, 2). Therefore, in recent years, Ni-advanced weathering steels have been widely used in coastal engineering of tropical atmospheric environment (Ref 3, 4). Moreover, it is generally believed that NiFe 2 O 4 precipitated at an initial stage of the reaction provided a location for the nucleation of the Fe(O,OH) 6 nano-network, thereby forming a film composed of dense fine particles (Ref 5, 6). The presence of NiFe 2 O 4 in nano-network changed the ion exchange performance of the corrosion product film and made it have the selectivity from anion to cation, thus effectively hindering the penetration of chloride ions and improving the corrosion resistance of Ni- containing steel (Ref 7, 8). In general, the outdoor field exposure experiments can better reflect the corrosion situation and the application effect of steel in the actual environment. Up to now, there have been many researches on the influence of Ni on the corrosion behaviors of weathering steels under the outdoor exposure experiment of marine atmosphere in different countries. For example, Palsson et al. (Ref 9) investigated the corrosion resistance of weathering steel in the tropic atmosphere of Thailand for 3 years. They concluded that the alloying elements of Cu, Cr and Ni could be improved the corrosion resistance of the steels when exposed in the high-Cl  concentration environment. Cano et al. (Ref 10) analyzed the characterization of the corrosion behavior of Ni- Cu-Cr weathering steel exposed in different atmospheres of Spain for 2 years and found that the corrosion rate value was the lowest when the Ni concentration was higher, especially in the marine atmosphere. Simultaneously, Ni tended to be enriched in the whole rust layer. Cheng et al. (Ref 11) studied the corrosion behaviors of Ni-containing weathering steels under the outdoor exposure experiment of marine atmosphere in China, and the results showed that the corrosion resistance of Ni-containing weathering steel was enhanced as the Ni content increased; 3.5 wt.% was the optimum Ni content to improve the corrosion resistance. Wu et al. (Ref 12) obtained the corrosion resistance of Ni-advanced weathering steel in a marine atmosphere of Male Island and found that the corrosion potential of the rust layer was low in the outer layer, while comparatively high in the inner layer. Ni was significantly enriched in the inner rust layer in the form of the NiFe 2 O 4 , which contributed to enhance the corrosion resistance of steels. In summary, the effect of alloying element Ni on the corrosion performance of Ni-containing weathering steel was closely related to the corrosive environment. In general, the harsher the corrosive environment, the more obvious the protection of alloying element Ni (Ref 13-15). For instance, in the high-humidity, high-temperature and chlorine-containing marine atmosphere, the change of wet/dry alternating will cause the damage to the structure, composition and property of the rust layer on steel matrix in outdoor exposure (Ref 16-18). However, the effects of corrosion kinetics and structure of corrosion products on the corrosion resistance of Ni-containing steels in different exposure periods are unclear. With the development of the ‘‘Belt and Road’’ policy in China, the construction of railways and bridges in Southeast Asian countries such as Thailand is gradually advancing and a lot of Ni-advanced steels will soon be applied to the tropical marine atmospheric environment. There is still a lack of in- depth understanding of the corrosion performance of Ni- Yueming Fan, Wei Liu, Zongteng Sun, Yonggang Zhao, Baojun Dong, Tianyi Zhang, Wongpat Banthukul, and Xiaogang Li, Corrosion and Protection Center, Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, PeopleÕs Republic of China; and Thee Chowwanonthapunya, Faculty of International Maritime Studies, Kasetsart University, Sriracha, Chonburi 20230, Thailand. Contact e-mail: weiliu@ustb.edu.cn. JMEPEG ÓASM International https://doi.org/10.1007/s11665-020-05153-6 1059-9495/$19.00 Journal of Materials Engineering and Performance