ORALS

SESSION: CorrosionMonPM2-R7	Macdonald International Symposium (Intl Sympos. on Corrosion for Sustainable Development)
Mon. 28 Nov. 2022 / Room: Andaman 2
Session Chairs: Harpreet Singh; Session Monitor: TBA

17:10: [CorrosionMonPM212] OS
Crevice Corrosion Behavior of Multiphase Steels Consisting of Various Phase Fraction of Bainite, Retained Austenite, Intercritical Ferrite and Pearlite
V Neetu¹ ; Sandeep Sangal¹ ; Kallol Mondal¹ ; ¹IIT Kanpur, Kanpur, India;
Paper Id: 200 [Abstract]

Now-a-days, high Si steel with bainitic structure has wide applications in railway and automobile industries due to its properties of high strength, high ductility and high toughness. These properties of the bainitic steels can be varied by the variation of austempering temperature and time [1, 2]. The present work represents the crevice corrosion behavior of a set of newly developed high strength and highly ductile multiphase steels consisting of various fractions of bainite, retained austenite (RA), intercritical ferrite (IF) and pearlite. The steels were made by various combinations of continuous cooling in the ferrite-pearlite zone followed by isothermal heat treatment in the bainite zone. Crevice corrosion tests of the multiphase steel specimens were carried out in 3.5 wt.% NaCl solution for 9 months. Steel rusts after crevice tests were analysed with the help of scanning electron microscopy (SEM), Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR). Ultrasonically cleaned multiphase steel specimens were characterized with the help of SEM and optical profilometry. Multiphase interaction and rust constituents uniquely control the crevice corrosion behaviour of the steels. Considering the effect of various fractions of bainite, RA, IF and pearlite present in the multiphase steels and their tendency to form the galvanic cell corrosion, it has been observed that the multiphase steel isothermally heat treated at 300℃ after 0 s of continuous cooling time from austenitization temperature shows less corrosion. Though, all the multiphase steel specimens have same identical chemical composition, they exhibit different modes and various degrees of corrosion attack due to the difference in the microstructures, morphological distribution and fraction of different constituent phases and their subsequent formation of micro galvanic couples. The combination of high strength and ductility in association with excellent crevice corrosion resistance of the multiphase steels implies its great potential in rail applications.

References:
[1] A. Varshney, S. Sangal, S. Kundu, K. Mondal, Super strong and highly ductile low alloy multiphase steels consisting of bainite, ferrite and retained austenite, Mater. Des. 95 (2016) 75–88.\n[2] A.P. Moon, S. Sangal, S. Layek, S. Giribaskar, K. Mondal, Corrosion behavior of high-strength bainitic rail steels, Metall. Mater. Trans. A 46 (2015) 1500–1518.

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: 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

12:20: [CorrosionTueAM03] OS
Enhanced Corrosion Resistance of Harmonic Structured Cantor Alloy in Hank’s Simulated Body Fluid Solution
Debdipta Banik¹ ; Kei Ameyama² ; Kallol Mondal³ ; ¹IIT Kanpur, Kanpur nagar, India; ²Ritsumeikan University, Kusatsu, Japan; ³IIT Kanpur, Kanpur, India;
Paper Id: 214 [Abstract]

High entropy alloys are one of the advanced materials with five or more elements forming a single phase. Earlier studies have shown that these alloys get their advanced properties due to four core effects: (i) high entropy effect, (ii) severe lattice distortion effect, (iii) sluggish diffusion effect, and (iv) cocktail effect. The available HEAs mainly contain d-block elements, such as Al, Cr, Mn, Fe, Co, Ni, Ti, Mo, etc. Microstructures, morphology, and distribution of constituent phases, like bi-modal microstructure, can improve the properties of materials to a great extent. In the last few years, the group of K. Ameyama of Ritsumeikan University, Japan, has come up with a new type of bi-modal microstructure, known as harmonic microstructure, where very fine and coarse grains distribute in a regular and periodic fashion [1]. It has been found that harmonic structured 316L stainless steel and 304L stainless steel show better corrosion resistance and wear resistance than their non-harmonic counterparts [2-5]. Our study deals with Cantor alloy (FeCrMnNiCo), whose grain size has been modified to harmonic microstructure. Scanning electron micrographs show the distinguished regions containing clusters of larger grains known as core and the network of fine grains known as shell. It has been confirmed by X-ray diffraction that a single FCC phase is present in the core and the shell regions. Corrosion properties of the Cantor alloy in simulated body fluid solutions are yet to be explored in literature. Hence, corrosion behavior has been carried out on the harmonic structured Cantor alloy and compared with its non-harmonic counterpart and harmonic structured 316L stainless steel, which is well known for its biological applications and harmonic structured 316L shows similar corrosion behavior but better wear resistance than the conventional 316L stainless steel. It has been found out in our study that the corrosion resistance of the harmonic structured Cantor alloy is greater than the non-harmonic one and comparable to that of the harmonic 316L stainless steel. Enrichment of Cr in the fine-grained shell region of harmonic structured Cantor alloy is attributed to the greater corrosion resistance of the alloy.

References:
S. K. Vajpai, M. Ota, Z. Zhang, K. Ameyama, Mater. Res. Lett. 4 (2016), 191-197.

PK Rai, S Shekhar, M Nakatani, M Ota, SK Vajpai, K Ameyama, K Mondal, JMEP 26 (2017), 2608-2618.

PK Rai, S Shekhar, M Nakatani, M Ota, SK Vajpai, K Ameyama, K Mondal, Metall. Mater. Trans. A 27 (2016), 6259-6269.

PK Rai, S Shekhar, K Yagi, K Ameyama, K Mondal, Wear 424 (2019), 23-32.

PK Rai, S Shekhar, K Yagi, K Ameyama, K Mondal, JMEP 28 (2019), 7554–7564.

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.