Galvanic interactions of HE15 /MDN138 & HE15 /MDN250 alloys in natural seawater

Abstract

HE15 is a heat treatable high strength alloy with excellent machinability find wide applications in aerospace and defence industries. In view of their excellent mechanical properties, workability, machinability, heat treatment characteristics and good resistance to general and stress corrosion cracking, MDN138 & MDN250 have been widely used in petrochemical, nuclear and aerospace industries. The galvanic corrosion behaviour of the metal combinations HE15 /MDN138 and HE15 /MDN250, with 1:1 area ratio, has been studied in natural seawater using the open well facility of CECRI’s Offshore Platform at Tuticorin for a year. The open circuit potentials of MDN138, MDN250 and HE15 of the individual metal, the galvanic potential and galvanic current of the couples HE15 /MDN138 and HE15 /MDN250 were periodically monitored throughout the study period. The calcareous deposits on MDN138 and MDN250 in galvanic contact with HE15 were analyzed using XRD. The electrochemical behaviors of MDN138, MDN250 and HE15 in seawater have been studied using an electrochemical work station. The surface characteristics of MDN138 and MDN250 in galvanic contact with HE15 have been examined with scanning electron microscope. The results of the study reveal that HE15 offered required amount of protection to MDN138 & MDN250.

Keywords

alloy / MDN138 / MDN250 / HE15 / galvanic corrosion / natural seawater

References

[1] ASTM International Standard practice for preparing, cleaning, and evaluating corrosion test coupons, 2011

[2] Brooks RR, Presley BJ, Kaplan IR. APDC-MIBK extraction system for the determination of trace elements in saline waters by atomic absorption. Talanta, 1967, 14(7): 806-816

[3] Culberson CH. Effect of seawater chemistry on the formation of calcareous deposits, 1983

[4] Dexter SC, Lafontaine JP. Effect of natural marine biofilms of galvanic corrosion. Corrosion, 1989, 54(11): 851-861

[5] Dickinson WH, Caccavo F, Lewandowski Z. The ennoblement of stainless steel by manganic oxide biofilms. Corrosion Science, 1996, 38(8): 1407-1422

[6] Edyvean RGJ. Interactios between microfouling and the calcareous deposit formd on cathodically protected steel in seawater. 6th Intl Cong Marine Corrosion and Fouling, 1987, 469-475

[7] Hack HP, Guanti RJ. Effect of high flow on calcareous deposits and cathodic protection current density. Materials Performance, 1989, 28(3): 29-35

[8] ASM Hutchings FR, Unterweiser PM. Exfoliation corrosion of HE.15 aluminium alloy. Failure analysis: The British Engine Technical Reports, 1981

[9] Hutchings FR, Unterweiser PM. Exfoliation corrosion of HE.15 aluminium alloy. Failure analysis: The British Engine Technical Reports, American Society for Metals, 1981

[10] Kciuk M, Tkaczyk S. Structure, mechanical properties and corrosion resistance of AlMg5 and AlMg1Si1 alloys. Journal of Achievements in Materials and Manufacturing Engineering, 2007, 21(1): 39-42

[11] Kunjapur M, Hartt W, Smith S. Influence of temperature on calcareous deposition cathodically polarized steel in seawater, 1985

[12] Lee R, Ambrose J. A hydrodynamical and chemical study of calcareous deposits, 1986

[13] Little BJ, Wagner PA. The interrelationship between marine biofouling and cathodic protection, 1993

[14] Liu H. Mechanical properties and corrosion behaviors of novel Cr2Ni Low-alloy construction steel. International Journal of Electrochemical Science, 2015, 10(3): 2130-2140

[15] Mohan Reddy T, Subanandha Rao A, Sambasiva Rao M. Design and development of propulsion system for antitank guided missile. Defence Science Journal, 1995, 45(3): 213-219

[16] Osorio RW, Noe C, Peixoto CL, Amauri G. Corrosion resistance and mechanical properties of an Al 9wt% Si alloy treated by laser surface remelting. International journal of electrochemical science, 2009, 4(6): 820-831

[17] Sarlak M, Shahrabi T, Zamanzade M. Investigation of calcareous deposits formation on copper and 316L stainless steel under cathodic polarization in artificial seawater. Protection of Metals and Physical Chemistry of Surfaces, 2009, 45(2): 216-222

[18] Strickland JDH, Parsons TR. A practical handbook of seawater analysis, 1972, Ottawa: Fisheries Research Board of Canada, 310

[19] Subramanian G, Parthiban GT, Muthuraman K, Ramakrishna rao P. Galvanic corrosion behaviour of HE20/MDN138 & HE20/MDN 250 alloys in natural seawater. Journal of Marine Science and Application, 2016, 15(3): 343-348

[20] Wieng SM, Osvoll H, Gartland PO, 2007. Efficient cathodic protection to stainless steel small bore tubing. Corrosion 2007, Houston, Paper No. 07078.