The main aim of the present work is to investigate the high-temperature corrosion behavior of bare, high-velocity oxy-fuel coated on iron-based superalloy A-286. Ni-20%Cr and Cr3C2-25%NiCr powders are deposited on the Fe based superalloy A-286 material by high-velocity oxy-fuel (HVOF) process. Surface roughness and coating thickness of the coated specimen is evaluated using surface roughness tester and optical microscope (OM). The hot corrosion study was performed on bare, and HVOF coated Fe-based superalloy A-286 in Na2SO4-50%V2O5-10%NaCl environment at 700 °C under cyclic conditions. Kinetics of corrosion has been determined by thermo-gravimetric analysis using mass change measurement; Cr3C2-25%NiCr coating shows the better corrosion resistance due to the formation of stable Cr2O3 layer. The uncoated superalloy is severely suffered by spallation and sputtering of oxide scales during hot corrosion study. The surface microstructure, chemical composition and phase identification of coatings before and after hot corrosion are analyzed using scanning electron microscope/ energy dispersive spectroscopy (SEM/EDS) and X-ray diffraction (XRD) analysis. Depth of corrosion attack and oxide scales are characterized using EDS compositional analysis and elemental mapping technique. The result of the cross-sectional image shows that uncoated material was severely suffered by hot corrosion to a depth of 200 µm. © 2019 Elsevier Ltd

Arivarasu M

Department of Design and Automation

School of Mechanical Engineering

Vellore Campus

Muthu S.M

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Engineering Failure Analysis

The present research work investigates the air oxidation and hot corrosion behavior of bare and CO2 laser welded Fe-based superalloy A-286 in air and in simulated aero engine molten salt (Na2SO4–7.5%NaVO3–5%NaCl) environment at 700 °C for 50 cycles. Spalling of oxide scales is observed in laser weldment in molten salt environment during hot corrosion study which is not observed in air-oxidized weldments at the end of 50 cycles. Corrosion kinetics of the weldments is obtained using the thermogravimetric technique. Scanning electron microscope/energy-dispersive spectroscopy and X-ray diffraction method are used to characterize the surface morphology and phase identification of the oxidized and hot-corroded weldments. Also, cross-sectional investigation is performed on the hot-corroded weldments to analyze the oxide scale thickness and distribution of alloying elements by optical/SEM microscopic and X-ray mapping analysis. The results show that higher corrosion rate is observed in the base metal compared to the weld zone and weldment. The grain refinement in the fusion zone facilitates the formation of Cr2O3 resulting in improved corrosion resistance in the fusion zone. © 2019, The Indian Institute of Metals - IIM.

Transactions of the Indian Institute of Metals

Air Oxidation and Hot Corrosion Behavior of Bare and CO2 Laser-Welded Superalloy A-286 at 700 °C

High temperature corrosion resistance of welded components in power plant industry, hot sections of gas turbines, boilers, industrial waste incinerators, metallurgical furnaces and petrochemical installations is one of the serious necessity. The failure of hot sections of welded component is due to the deposition of molten salt which accelerates the hot corrosion reactions in the weld joint. In this research work, the oxy-chlorination of dissimilar weldments between AISI 304L austenitic stainless steel and AISI 4340 alloy steel at 600°C in eutectic mixture of K2SO4 + 60% NaCl under molten salt conditions was investigated. Corrosion kinetics for this dissimilar joints calculated from the thermogravimetric charts were represented. Corrosion on the dissimilar joint employing E309L filler in pulsed current gas tungsten arc welding process is found to be very aggressive, due to the fragmented delta ferrites at numerous locations resulting in the formation of the micro electrochemical cells, which act as sites for corrosion initiation and thus leading to higher corrosion rate. However, in the case of continuous current, the joint is able to protect itself better in this environment due to lower amounts of delta ferrites in weld zone, which is attributed to the higher temperature available in continuous mode leading to austenisation of delta ferrites in the multipass welding. © 2017 Institute of Materials, Minerals and Mining Published by Taylor &amp; Francis on behalf of the Institute.

Corrosion Engineering, Science and Technology

Hot-corrosion resistance of dissimilar AISI 4340 and AISI 304L weldments in the molten salt environment at 600°C

Hot corrosion behavior of porous nickel-based alloys containing molybdenum in the presence of NaCl at 750 °C

Materials Science and Engineering: A

Combined effect of resistance spot welding and precipitation hardening on tensile shear load bearing capacity of A286 superalloy

Journal of Minerals and Materials Characterization and Engineering

Hot Corrosion Behavior of Superalloy in Different Corrosive Environments

Investigations of hot corrosion resistance of HVOF coated Fe based superalloy A-286 in simulated gas turbine environment

Journal	Data powered by TypesetEngineering Failure Analysis
Publisher	Data powered by TypesetElsevier BV
ISSN	1350-6307
Open Access	0