Effect of Molybdenum on the Corrosion of Low Alloy Steels in Synthetic Seawater
Materials Transactions, Vol. 57, No. 12 (2016) pp. 2116 to 2121 ©2016 The Japan Institute of Metals and Materials Effect of Molybdenum on the Corrosion of Low Alloy Steels in Synthetic Seawater Su-Bin Shin1, Sol-Ji Song1, Young-Woong Shin1, Jung-Gu Kim1,*, Byung-Joon Park2 and Yong-Chan Suh2 1Department of Advanced Materials Science and Engineering, Sungkyunkwan University, 300 Chunchun-dong, Jangan-gu, Suwon, South Korea 2Heavy Plate R&D Team of R&D Center, Hyundai-Steel Company, 167–32 Kodae-Ri, Songak-Eup, Dangjin 343–823, South Korea The alloying effect of Mo on the seawater immersion corrosion for low alloy steel was investigated using weight loss tests and electro- chemical impedance spectroscopy (EIS) in seawater. The Mo-containing low alloy steel showed an excellent corrosion resistance by the long immersion test due to the formation of homogeneous rust layer preventing active dissolution. SEM and XPS analyses were conducted to observe cross-sectional images of rust layer and indentify chemical composition of oxide formed on the surface after immersion test. The results revealed 2− that the MoO4 ions which were oxidized from Mo form the compounds which disturb the approach of aggressive ions. [doi:10.2320/matertrans.M2016222] (Received June 17, 2016; Accepted September 15, 2016; Published October 21, 2016) Keywords: corrosion resistance, electrochemical impedance spectroscopy, molybdenum, seawater, X-ray photoelectron spectroscopy 1. Introduction gen reduction reaction which occurs at the interface of oxide and electrolyte is decreased.16) In other words, the electronic High strength low alloy (HSLA) steels, which provides properties of the oxide affect the rate of oxygen reduction high mechanical properties, weldability and corrosion resis- reaction and corrosion rate.17) Therefore, the study on the rust tance, are widely used as structural material such as bridge, layer is important for the design of the corrosion-resistant building, pipe line and so on.
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