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JMEPEG DOI: 10.1007/s11665-017-2723-6

Corrosion Behavior of Low-C Medium-Mn Steel in Simulated Marine Immersion and Splash Zone Environment Dazheng Zhang, Xiuhua Gao, Guanqiao Su, Linxiu Du, Zhenguang Liu, and Jun Hu (Submitted November 4, 2016; in revised form April 25, 2017) The corrosion behavior of low-C medium-Mn steel in simulated marine immersion and splash zone environment was studied by static immersion corrosion experiment and wet-dry cyclic corrosion experiment, respectively. Corrosion rate, corrosion products, surface morphology, cross-sectional morphology, elemental distribution, potentiodynamic polarization curves and electrochemical impedance spectra were used to elucidate the corrosion behavior of low-C medium-Mn steel. The results show that corrosion rate in immersion zone is much less than that in splash zone owing to its relatively mild environment. Manganese compounds are detected in the corrosion products and only appeared in splash zone environment, which can deteriorate the protective effect of rust layer. With the extension of exposure time, corrosion products are gradually transformed into dense and thick corrosion rust from the loose and porous one in these two environments. But in splash zone environment, alloying elements of Mn appear significant enrichment in the rust layer, which decrease the corrosion resistance of the steel. Keywords

corrosion behavior, low-C medium-Mn steel, static immersion, splash zone, wet-dry cyclic

1. Introduction Nowadays, the chemical composition design method of high-strength structural steel used in marine engineering is mostly low-C, low-Mn and addition of Ni, Mo, Cr elements with large scale. But addition of expensive alloying elements, such as Ni and Mo leads to an increase in cost. In order to reduce the cost, many researchers (Ref 1-5) made a lot of studies on ‘‘Mn/ C’’ alloying steel and aimed at exploiting new-type highstrength high-toughness structural steel by replacing expensive Ni with inexpensive Mn. Hu et al. (Ref 5, 6) have successfully developed high-strength and high-toughness low-carbon medium manganese steel. This steel owns great potentiality to apply in offshore structures, ship plates and bridges because of its low cost and excellent mechanical properties. But more recently, researches on low-C medium-Mn steel are mostly confined to the microstructure and mechanical properties. Its corrosion behavior in different environment has rarely reported. It is generally known that marine corrosion is an intractable problem and marine engineering structural steels suffer from marine corrosion due to the strong corrosive effect of corrosive ions in seawater. Thus, many researchers (Ref 7-11) have carried out a lot of experiments to study the corrosion behavior of Dazheng Zhang, Xiuhua Gao, Guanqiao Su, Linxiu Du, and Jun Hu, The State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819, Peoples Republic of China; and Zhenguang Liu, School of Material Science and Engineering, Jiangsu University of Science and Technol