ORIGINAL CONTRIBUTION Recreation of Marine Atmospheric Corrosion Condition on Weathering Steel in Laboratory S. K. Guchhait • S. Dewan • J. K. Saha • P. K. Mitra Received: 13 March 2014 / Accepted: 25 April 2014 / Published online: 17 May 2014 Ó The Institution of Engineers (India) 2014 Abstract Salt spray test, autoclave corrosion test, SO 2 salt spray test, and Relative humidity test are generally used to assess atmospheric corrosion in laboratories at accelerated rates. However, no test can absolutely simulate the service condition. One can get only approximate cor- rosion rates using the aforesaid tests which serve as an indicative of corrosion behavior of the material in a service condition. The present work is aimed at creating specific environmental condition in laboratory to get the corrosion test done in short duration to compare with on field exposure test which would otherwise take years to com- plete. In this work recreation of atmospheric environment of Digha was tried and it was simulated in such a manner that the results of laboratory test could be compared with long time field exposure at Digha. Weathering steel (WS) was taken for experimentations. Potentiostatic electro- chemical tests route was adopted to simulate atmospheric condition of Digha. Laboratory test results compared well with 18 month field exposure data in terms of corrosion rate, SEM and Ramon Spectroscopy matching. Keywords Weathering steel Á Laboratory simulation Á Corrosion Á Field test Á SEM Á Raman spectroscopy Introduction Panossian et al. [1] showed that weathering steels (WS) have 1–2.5 % of alloying elements especially Cu, Cr, P etc. and have a tendency to form a specific type of rust which helps in decreasing the corrosion rate after long exposures. The rate of rust formation depends on the access of oxygen in the presence of moisture and air. According to Saha [2] rust formation process slows down as the process pro- gresses because the rust layers acts as a barrier to the ingress of the oxygen. In WS the rust layer is more adherent in nature and reduces the rate of rust growth. From Pourbaix [3] concept, it has been seen that the typical behavior of WS is due to the passivation during drying and lack of activation during wetting. Feliu et al. reported that air borne chloride (0.5 mg/100 cm 2 /day), average wetness time \ 60 %, industrial pollutants (SO 2 \ 2.1 mg/100 cm 2 / day) are the favorable parameters to form a stable rust on WS [4, 5]. Marine atmosphere have high percentage of relative humidity and airborne salt. Corrosion rate in chloride environment gets reduced in special grade WS. Many authors have studied the corrosion products formed on carbon and WS when they are exposed to different atmo- sphere [6–14]. On WS, major rust phase lepidocrocite (c- FeOOH) transforms to the more stable goethite (a-FeOOH). With increasing exposure time, continuous transformation of a-FeOOH occurs to either protective c Fe 2 O 3 or a Fe 2 O 3 as well as amorphous d FeOOH [2]. Pourbaix diagram [3] for iron-Na 2 SO 4 shows passivity between pH 9 and 12.5 due to formation of iron hydroxide. Saha [2] reported that when WS are exposed to the marine environment at Digha a protective layer of a Fe 2 O 3 , c Fe 2 O 3 , c FeOOH, d FeOOH and a Fe 2 O 3 , a FeOOH, c FeOOH are formed during 18 and 42 months on field exposure respectively. S. K. Guchhait (&) Á S. Dewan Á P. K. Mitra Department of Metallurgical & Material Engineering, Jadavpur University, Kolkata 700032, India e-mail: sujitguchhait.chem@gmail.com J. K. Saha Institute for Steel Development & Growth (INSDAG), Kolkata 700019, India 123 J. Inst. Eng. India Ser. D (January–June 2014) 95(1):43–47 DOI 10.1007/s40033-014-0039-3