CORROSIVE INFLUENCE OF VARIED SALT SOLUTIONS CONCENTRATION ON MILD STEEL

Abstract

This study is focused on the corrosive effects of varied salt solutions concentration on two mild steel specimens (API 5L X42 and API 5L X60). Gravimetric method was adopted in the evaluation of the weight loss and corrosion rate of the specimens. The hardness of the test specimens after dipping in corrosive solutions was examined. Potentiodynamic polarisation technique was also used to compare the most corrosive medium. API 5L X42 and API 5L X60 specimens exhibited highest corrosion rates of 9.593 mmpy and 9.698 mmpy respectively in solution A that contained 2.0 M NaCl, 3.0 M CaCl2 and 0.5 M Na2CO3. They also exhibited the lowest corrosion rates of 7.642 mmpy and 7.836 mmpy respectively, in solution H that contained 0.5 M NaCl, 3.0 M CaCl2 and 2.5 M Na2CO3. The API 5L X42 mild steel specimen in solution H exhibited the highest hardness value of 369 HV after immersion in the corrosive medium. The hardness of the corroded specimens decreased when compared to their hardness before immersion in the corrosive media, which indicates that the varied salt solutions impaired the surface morphology of the specimens’ thereby promoting indentation.

Keywords

• Mild steel
• Corrosion rate
• Salt solutions
• Molar concentration
• Potentiodynamic polarisation
• Hardness

References

1. 1. May M. Corrosion behaviour of mild steel immersed in different concentrations of NaCl solutions. Journal of Sebha University – (Pure and Applied Sciences), 2016;15(1):1- 12.
2. 2. Amir P. Corrosion of steel bars in saturated Ca(OH)2 and concrete pore solution. Concrete Research Letters, 2010;1(3):90-97.
3. 3. Kanimozhi KR, Shyamala R, Sankara P, Jian Li. Effect of sodium chloride concentration on the corrosion of carbon steels and stainless steels in CO2 environment at atmospheric pressure under turbulent flow condition. National Association of Corrosion Engineers (NACE), NACE International, 2014;4074:1-16.
4. 4. Oladele S, Okoro HK. Investigation of corrosion effect of mild steel on orange juice. Afr. J. Biotechnol., 2011;10(16):3152-3156.
5. 5. Rita M, Aditi S. Cast iron deterioration with time in various aqueous salt solutions. Bull Mater. Sci., 2002;25(1):53-58.
6. 6. Durowaye SI, Alabi AGF, Sekunowo OI, Bolasodun BO, Rufai OI. Inhibitive effect of sodium sulphite on corrosion of mild steel in borehole water containing 1M sodium hydroxide solution. American Journal of Materials Science (AJMS), 2014;4(1):11-17.
7. 7. Ibrahim MFB. Effect of different sodium chloride (NaCl) concentration on corrosion of coated steel. BSc Thesis, Faculty of Mechanical Engineering, Universiti Malaysia, Pahang, Malaysia, 2013.
8. 8. Gao S, Jin P, Brown B, Young D, Nesic S, Singer M. Corrosion behavior of mild steel in sour environments at elevated temperatures. National Association of Corrosion Engineers (NACE), NACE International, Conference Paper No. 9084, New Orleans, Louisiana, USA, 2017.

9. 9. Kanimozhi KR, Shyamala R, Sankara P, Jian Li. Effect of sodium chloride concentration on the corrosion of carbon steels and stainless steels in CO2 environment at atmospheric pressure under turbulent flow condition. National Association of Corrosion Engineers (NACE), NACE International, 2014;4074:1-16.
10. 10. Standard practice for preparing, cleaning, and evaluating corrosion test specimens. American Society for Testing and Materials (ASTM), PA, USA, 2017.
11. 11. Ikechukwu AS, Obioma E, Ugochukwu NH. Studies on corrosion characteristics of carbon steel exposed to Na2CO3, Na2SO4 and NaCl solutions of different concentrations. International Journal of Engineering and Science, 2014;3(10):48-60.
12. 12. Cinitha A, Umesha PK, Iyer NR. An overview of corrosion and experimental studies on corroded mild steel compression members. KSCE Journal of Civil Engineering, 2014;18(6):1735-1744.
13. 13. Standard test method for conducting potentiodynamic polarization resistance measurements, ASTM International, West Conshohocken, PA, USA, 2014.
14. 14. Standard practice for calculation of corrosion rates and related ınformation from electrochemical measurements. American Society for Testing and Materials (ASTM), West Conshohocken, PA, USA, 2015.
15. 15. Standard test method for Vickers hardness of metallic materials. American Society for Testing and Materials (ASTM), 100 Barr Harbor Dr.,West Conshohocken, PA 19428, USA, 1997.
16. 16. Ayoola WA, Bodude MA, Onovo H, Akinlabi O. Effect of zinc powder addition to villa and silka marine enamel paints on corrosion resistance of mild steel. Nigerian Journal of Technology (NIJOTECH), 2018;37(1):158-166.
17. 17. Andi R, Muhammad A, Enriko F, Norman S. Corrosion rate of carbon steel for flowline and pipeline as transmission pipe in natural gas production with CO2 content. Makara of Technology Series, 2012;16(1):57-62.
18. 18. Oloruntoba D.T. Corrosion inhibition of Na2CO3 on low carbon steel in Ureje seawater environment. Leonardo Electronic Journal of Practices and Technologies, 2016;28:47-56.
19. 19. Alves VA, Brett CMA. Characterisation of passive films formed on mild steels in bicarbonate solution by EIS. Elsevier, Electrochimica Acta, 2002;47:2081-2091.
20. 20. Saba NE, Yoon-Seok C, David Y, Srdjan N. Effect of calcium on the formation and protectiveness of iron carbonate layer in CO2 corrosion. NACE International Corrosion Conference and Expo, 2013;2358:1-13.
21. 21. Liu Y, Zhou X, Thompson GE, Hashimoto T, Scamans GM, Afseth A. Precipitation in an AA6111 aluminium alloy and cosmetic corrosion. Acta Mater., 2007;55:353–360.
22. 22. Nor-Asma RBA, Yuli PA, Mokhtar CI. Study on the effect of surface finish on corrosion of carbon steel in CO2 environment. Journal of Applied Sciences, 2011;11:2053-2057.