An experimental model for simulating the corrosion of carbon steel fasteners(bolt and nut)composed of a contact carbon steel electrode(CCSE)and an exposed bare carbon steel plate electrode(BCSE)was designed.The effect of coupling on the corrosion process of the galvanically coupled carbon steel electrode was evaluated and compared with the self-corrosion process observed independently at the exposed and contact regions.Results obtained indicated that at an equal area ratio and uncoupled conditions,the corrosion rate is accelerated in the surface directly exposed to bulk solution compared to the bolt surface in contact with the nut.A coupling current was recorded when the exposed surface(BCSE)was electrically con-nected with the contact surface(CCSE);with the CCSE acting as the anode thereby suppressing the corrosion process in the exposed surface.By implication,the galvanic coupling between CCSE and BCSE increased the corrosion rate of CCSE.The difference in oxygen supply was responsible for the coupling effect observed in the system as there was no decrease in the solution pH.Moreover,varying the cathode-to-anode area(Sc/Sa)ratio significantly influenced the corrosion current density as increased Sc/Sa ratio resulted in an accelerated galvanic corrosion process.The corroded surfaces and interfaces were analysed using stereomicroscopy and scanning electron microscopy.X-ray diffractometry was adopted for corrosion prod-uct characterization.The results obtained showed supportive evidence of the corrosion behaviour in carbon steel fasteners.

Enobong Felix Daniel;Junhua Dong;Xiaofang Li;Ini-lbehe Nabuk Etim;Inime Ime Udoh;Rongyao Ma;Lei Chen;Changgang Wang

Shenyang National Laboratory for Materials Science,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China;School of Materials Science and Engineering,University of Science and Technology of China,Shenyang 110016,China;School of Materials Science and Engineering,Northeastern University,Shenyang 110819,China;Department of Marine Biology,Akwa Ibom State University,P.M.B 1167,Uyo,Nigeria;School of Environmental and Chemical Engineering,Shenyang Ligong University,Shenyang 110159,China

金属学报（英文版）

[1]Enobong Felix Daniel;Junhua Dong;Xiaofang Li;Ini-lbehe Nabuk Etim;Inime Ime Udoh;Rongyao Ma;Lei Chen;Changgang Wang-.Corrosion Behaviour of Carbon Steel Fasteners in Neutral Chloride Solution)[J].金属学报（英文版）,2022(04):563-576

Fasteners,CCSE,BCSE,galvanically,stereomicroscopy

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