Faculty Publications
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Item Influence of green inhibitor on flow-accelerated corrosion of API X70 line pipe steel in synthetic oilfield water(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2020) Ajmal, T.S.; Arya, S.B.; Thippeswamy, L.R.; Quraishi, M.A.; Haque, J.Inhibition effect of oleic acid hydrazide (OAH), a green corrosion inhibitor on API X70 steel in an Indian oilfield produced water was investigated for the first time under flow condition. The test was carried out at a more critical location (90-degree pipe elbow) in a circulating loop system with the fixed flow velocity. This location is deliberately chosen because, at this location, catastrophic failure of a low alloy steel piping system usually takes place under highly corrosive turbulent flow with higher wall shear stress and flow velocity. The corrosion examination was carried out by varying the concentrations (0.05, 0.15, 0.30 g L?1) of the OAH inhibitor under flow condition. The maximum inhibitor efficiency is found 87.7% at 0.30 g L?1 concentration. The formation of protective film was confirmed by SEM, XPS, Raman spectroscopy and FTIR spectra. © 2020, © 2020 Institute of Materials, Minerals and Mining Published by Taylor & Francis on behalf of the Institute.Item Influence of sample preparation techniques on microstructure and nano-mechanical properties of steel-concrete interface(Elsevier Ltd, 2020) Goudar, S.K.; Das, B.B.; Arya, S.B.; Shivaprasad, K.N.Interface between steel and concrete is characterized as highly porous and weakest region which influences both mechanical properties and durability of a reinforced concrete structure. The properties of the steel-concrete interface (SCI), especially the porous zone thickness are prime factors in predicting the time for corrosion initiation to corrosion cracking in service life prediction models. Measurement of porous zone thickness of reinforced concrete samples is sensitive to the sample preparation technique for microscopic observations. It is observed that there are hardly any research articles are available in the literature regarding the sample preparation technique of reinforced concrete sample for SCI analysis. In the present study, a detailed and stepwise sample preparation technique is proposed where there is minimal damage found to be observed to SCI. The major focus is on the speed of cutting tool that is being used for obtaining a relatively small size of sample from the bulk reinforced concrete member. The properties such as porous zone thickness and nano mechanical properties around the SCI were determined through scanning electron microscopy and nano-indentation, respectively. A significant variation in porous zone thickness around SCI was observed and measured value of average porous zone thickness is found to be approximately 1.8 times higher from high-speed cutting to low-speed. A similar kind of observation was noticed for nano mechanical properties. In addition to speed of cutting, there found to be other factors such as pressing force for specimen, duration of polishing and heating temperature has significant influence on interfacial properties. © 2020 Elsevier LtdItem Effect of hydrodynamics and laser surface melting on erosion-corrosion of X70 steel pipe elbow in oilfield slurry(Elsevier Ltd, 2022) Ajmal, T.S.; Arya, S.B.; Maurya, P.; Shariff, S.M.Erosion-corrosion (EC) is a significant cause of pipeline failure in the petrochemical industry. The influence of laser surface melting (LSM) on the EC of API X70 steel was investigated with simulated oilfield slurry (1.5 wt% silica sand). The slurry was circulated continuously in a closed-loop apparatus at 3 m/s velocity and EC tests were performed using electrochemical corrosion and weight loss measurements for the untreated and LSM (2.5 kW) samples located at a 90⁰ pipe elbow. Since the erodent particle velocity and the flow rate are low, the EC was dominated by corrosion. LSM samples exhibited higher EC resistance and hardness due to the surface metallurgy alteration and the EC rate varies within the pipe elbow. The primary reasons for the severe EC rates of electrodes placed at the downstream side of the elbow's extrados (outer face) are the secondary flow effect and higher sand concentration. © 2022 Elsevier LtdItem Biocorrosion Behavior of Epoxy-Based Multilayer Nanocomposite Coatings(Springer Science and Business Media Deutschland GmbH, 2023) Shetty, P.; Arya, S.B.; Shetty K, V.S.Marine structures are prone to biocorrosion, so developing a suitable coating system to combat corrosion is essential. The present work is focused on the development of a multilayered epoxy-based nanocomposite (NC) coating system reinforced with ZnO filler in the first layer coat (NC1), ZnO and Cu2O in the second layer (NC2), and the third layer consisting of a varying percentage of TiO2 with 5 wt%, 10 wt%, and 15 wt% of TiO2 designated as NC3, NC4, and NC5, respectively, as top coat on the bare steel. Brush coating was employed to fabricate the coatings. Surface morphology and mechanical properties, wettability, corrosion, and biocorrosion behavior of the bare steel and coated substrates were examined. Mechanical properties such as linear scratch hardness and posi adhesion test values of the coatings were found to be in the order NC1 < NC2 < NC3 < NC4 < NC5. The NC3-coating system comprising three layers of coating reinforced with 5 wt% TiO2 imparting hydrophobicity offered maximum resistance to microbial adhesion with 93% and 91% reduction in corrosion rate than the bare metal in natural and artificial seawater, respectively, after the 7th day of immersion. The bacterial and fungal cell counts in the biofilm after the 7th day of immersion were reduced by four and three orders of magnitude, respectively, in the nanocomposite against the bare substrate providing good biofouling resistance. NC3 coating also prevented the release of metal ions into the seawater and acted as a barrier for the leaching of metals from the coating underneath, thus, proving to be safe for the marine environment. © 2023, The Author(s), under exclusive licence to Springer Nature Switzerland AG.Item Hot corrosion behaviour of mullite thermal barrier coatings for marine diesel engines(Elsevier Ltd, 2024) K, S.; Babu, N.; Cadambi, S.; Arya, S.B.Mullite's inherent qualities have made it a potential material for the application of thermal barrier coatings (TBCs) for diesel engine components. Hot corrosion at 600–800 °C can cause TBC degradation, thus significantly affecting the performance of engine components and reducing their service life. This work examines the hot corrosion behaviour of atmospheric plasma-sprayed (APS) mullite coating over NiCrAlY bond coat on mild steel substrates. The coated specimen surface was covered with a mixture of Na2SO4 (sodium sulphate) and V2O5 (vanadium pentoxide) in the form of paste and heated in a muffle furnace at 700 °C for up to 300 h. SEM, EDS, and XRD characterisations were used to investigate the mechanism of hot corrosion. Coatings remained intact after corrosion tests; however, it had reacted with corrosive salts, particularly sodium sulphate. This was evidenced by the removal of amorphous silica, followed by the formation of nosean as a major phase. During the reaction between sodium sulphate and mullite coating, vanadium pentoxide was found to be acting as a flux and mineraliser. © 2023 Elsevier Ltd and Techna Group S.r.l.Item Enhancing the Flow-Accelerated Corrosion Resistance of X70 API Steel Through Laser Surface Melting in Synthetic Oilfield Water(John Wiley and Sons Inc, 2025) Ajmal, T.S.; Singh, R.K.; Arya, S.B.; Kumar D, S.Hydrodynamic flow conditions play a critical role in piping failure due to sharp variations of the Reynolds number in process and petrochemical industries. The current study aims to enhance flow-accelerated corrosion (FAC) resistance using metallurgy of the surface by utilizing the laser surface melting (LSM) technique. The FAC behavior of API X70 steel in simulated Indian synthetic oilfield water was studied by utilizing a closed-loop corrosion apparatus to simulate the pipeline flow. Electrochemical corrosion experiments (AC and DC methods) were conducted at a constant fluid velocity of 3 m/s in untreated and LSM-treated samples (at 2.5 and 3.0 kW) placed at a 90° pipe elbow. Experimental results showed that LSM-treated samples displayed enhanced resistance to FAC, attributed to changes in surface metallurgy. Additionally, it was observed that the corrosion rate varied within the pipe elbow for the different samples at different locations. © 2024 Wiley-VCH GmbH.Item Meltpool characteristics, microstructure, and corrosion performance of laser-directed energy deposition cladded 316L SS/X70 steel for oilfield applications(Elsevier Ltd, 2025) Singh, R.K.; Arya, S.B.; Nayak, J.In oilfield pipeline transmission, complex geometries such as elbows, reducers, tees, and orifices face significant corrosion risks, especially in aggressive environments where multiphase turbulent flow and chloride ions cause sharp variations in hydrodynamic parameters. This study explores a laser cladding approach to mitigate internal corrosion in these complex geometries. The Laser-Directed Energy Deposition (L-DED) technique, known for its precision and efficiency, is employed to apply corrosion-resistant 316 L stainless steel (SS) over API X70 steel. Key parameters, including laser power and scan speed, were varied across nine combinations to evaluate their effects on melt pool characteristics, microstructure, and corrosion properties of the clads. Results showed that as laser energy increased (higher power and lower scan speed), melt pool dimensions and heat-affected zone (HAZ) thickness also increased, with clad thickness and HAZ ranging from 172 to 504 µm and 159–272 µm, respectively. Cellular and columnar sub-grain structures were present across all process combinations, with sub-grain size increasing at higher laser energy. A notable variation in chromium content was detected, with the clad produced at 500 W and 720 mm/min exhibiting superior pitting and corrosion resistance. This high-energy clad featured 16.3 % chromium and larger sub-grain sizes, facilitating stable passive film formation during corrosion. The optimized clad demonstrated approximately two orders better corrosion performance than the base X70 steel. © 2025Item Enhancing X70 steel durability: Tribo-corrosion resistance through protective laser cladding(Elsevier Ltd, 2025) Singh, R.K.; Bhole, K.B.; Arya, S.B.; Nayak, J.This study investigates the effects of laser surface cladding (L-DED technique) on the tribo-corrosion behavior of API X70 steel in the simulated Indian oilfield water. Using optimized parameters, 500 W laser power, 720 mm/min scan speed, and 4.2 g/min powder feed rate, 316 L SS was successfully clad onto X70 steel without any significant defects. The results showed a significant improvement in corrosion resistance, with the SS clad exhibiting a corrosion rate of 131.3 ?m/year at 20 N, compared to 287.9 ?m/year for the X70 substrate. SEM and 3D profilometer analyses revealed a more stable tribo-layer on the SS clad, with less damage and debris accumulation. These findings highlight the potential of laser cladding to enhance the durability and lifespan of steel components. © 2025 Elsevier Ltd