ORALS

SESSION: CorrosionTueAM-R7	Macdonald International Symposium (Intl Sympos. on Corrosion for Sustainable Development)
Tue. 29 Nov. 2022 / Room: Andaman 2
Session Chairs: Shujiang Geng; Session Monitor: TBA

11:30: [CorrosionTueAM01] OS
Rapid Assessment Of Corrosion Susceptibility Of Mild Steel In Simulated Splash Zone Condition
Vishwanath Kalikivayi¹ ; Kallol Mondal² ; Sudhanshu Shekhar Singh³ ; ¹Indian Institute of Technology Kanpur, Kanpur, India; ²IIT Kanpur, Kanpur, India; ³Indian Institute of Technology (IIT), Kanpur, KANPUR, India;
Paper Id: 202 [Abstract]

Mild steels or their derivative steels in the carbon range of 0.1-0.25%C are used in almost all the common engineering applications, such as construction, bridges, household, agriculture, etc. On the other hand, constructions in off-shore or river always experience hostile environment leading to severe corrosion of the steel structures as well as reinforced bars embedded in concrete structures [1]. Therefore, quick assessment of corrosion in laboratory scale is extremely important in order to facilitate the selection of suitable materials for varied corrosion environments in off-shore area [2, 3]. Hence, the present work concentrates on the quick evaluation of corrosion of a normalized mild steel under the influence of water line change due to wave as well as natural evaporation. A novel simulated marine environment device has been developed to evaluate the corrosion behavior in various marine zones (atmosphere zone, splash zone, and immersion zone). The Raman spectroscopic analysis of the corrosion products, formed at various zones, has revealed the formation of α-FeOOH, γ-FeOOH, β-FeOOH and Fe2O3 in a unique way. The morphologies of the corrosion product formed in various zones, as characterized by scanning electron microscope (SEM), show that the corroded region of the splash zone contains cracks and porous rust layer in comparison to that of the other regions, indicating instability of the corrosion products. Moreover, the thickness of the corrosion product layer is more in the splash zone in comparison to that of the other zones due to cyclic wetting and drying. In addition, open circuit potential (OCP) and linear polarization (LP) measurements, conducted on the corroded surface of various zones without the removal of the rust layer, suggest strong relationship of rust layer composition and phase fraction with OCP and LP.

References:
1. R. Jeffrey, R. E. Melchers, Corrosion Science, 51(10) (2009) 2291-2297.
2. J. Wu, K. Pang, D. Peng. Wu, Y. Bao, X. Li, Int. J. Electrochem. Science 12(2017) 1216-1231.
3. S. Choudhary, A. Garg, K. Mondal, Journal of Materials Engineering and Performance 25(7) (2016) 2969-2976.

SESSION: CoatingsTuePM2-R7	7th Intl. Symp. on Sustainable Surface & Interface Engineering: Coatings for Extreme Environments
Tue. 29 Nov. 2022 / Room: Andaman 2
Session Chairs: Maude Mermillion-Jimenez; Session Monitor: TBA

16:45: [CoatingsTuePM211] OS
Microstructural development and corrosion characteristics of prior copper coated hot dip galvanized dual phase steel
Harikrishna Kancharla¹ ; Gopi Kishor Mandal² ; Kallol Mondal³ ; Sudhanshu Shekhar Singh¹ ; ¹Indian Institute of Technology (IIT), Kanpur, KANPUR, India; ²CSIR - National Metallurgical Laboratory, Jamshedpur, India; ³IIT Kanpur, Kanpur, India;
Paper Id: 201 [Abstract]

Galvanised or Zn coated steel provides corrosion protection to underlying steel due to sacrificial effect of Zn, where Zn dissolves and Fe acts a cathodic part in the electrochemical reactions [1]. Galvanised steels are used in wide range of applications such as, constructions (rebar), beams, etc., piping industries, automobile industries, roof covers, etc. [1]. However, for many years, the galvanization of high strength steels brings a great challenge to galvanizers mainly due to selective surface oxidation of minor alloying elements (such as Si, Mn, Al etc.) present on the steel surface during annealing, which drastically reduces the wettability of liquid Zn on the steel surface [1-3]. In the present investigation, the role of copper (Cu) pre-coat has been studied for the development of good quality defect free hot dip galvanized (GI) coating on a dual phase (DP 590) steel substrate. The application of Cu pre-coating, prior to reduction annealing process, greatly influences the microstructural development of the GI coatings and corrosion behavior. The X-ray diffraction (XRD) analysis reveals the presence of hexagonal closed packed (hcp) structure in both the GI samples, with and without Cu pre-coating. Moreover, Cu pre-coated GI steel exhibits the pronounced texture coefficient (TC) of preferred high atomically dense (0002) crystal plane in comparison to without pre-coated GI steel sheet. High quality GI coating, free from any surface defects, is obtained on the Cu pre-coated steel substrate. However, coating quality is inferior on the steel substrate without Cu pre-coat due to the presence of several bare spots on the top surface of the coating. In addition, Cu pre-coated GI steel reveals the formation of a continuous iron aluminide (Fe-Al) intermetallic interfacial layer with uniform distribution of dense and equiaxed Fe-Al crystals at the interface between the substrate and the coating. It is also noted that the corrosion resistance of Cu pre-coated GI steel is superior as compared to the GI steel without pre-coat. It is concluded that the formation of a continuous compact interfacial layer along with highest atomically dense (0002) crystal plane has resulted in high quality defect free coating, facilitating to attain the lowest corrosion rate of Cu pre-coated GI steel.

References:
1. S.M.A. Shibli, B.N.Meena, R. Remya, Surface & Coatings Technology 262 (2015) 210–215.
2. Huachu Liu, Fang Li, Wen Shi, Srinivasan Swaminathan, Yanlin He, Michael Rohwerder, Lin Li, Surface & Coatings Technology 206 (2012) 3428–3436.
3. Yun-IL Choi, Won-Jin Beom, Chan-Jin Park, Doojin Paik, Moon-Hi Hong, Metallurgical and Materials Transactions A, 2010, Volume 41A, 3379-3385.