Papers by Keyword: Hot Corrosion

Abstract: In this research work, an attempt has been made to study the weldability of AISI 304L using filler materials ENiCu-7 and ENiCrMo-3 by Gas Tungsten Arc Welding (GTAW) process. Investigations are carried out on the metallurgical and mechanical properties of AISI 304L weldments. Further, cyclic hot corrosion studies are performed on the various zones of the weldment in air oxidation for 50 cycles at 600^ C. Thermogravimetric data is collected at the end of every cycle and the weldments are characterized using XRD analysis.

Abstract: This research work aims at investigating the performance of the gas tungsten arc welded dissimilar AISI 304 and AISI 310S when subjected to cyclic hot corrosion in air oxidation and in the molten salt environment of K₂SO₄ + 60% NaCl environment at 600°C. The weldments are characterized for its mechanical and metallurgical properties. Tensile strength of the weldment is found to be 529 Mpa. Further the hot corrosion studies are performed on the various zones of the weldment and the corrosion products are characterized by the combined techniques of optical microscopy, XRD and SEM/EDAX analysis.

Abstract: In this research work, an attempt has been made to study the weldability of AISI 304L using filler materials ENiCu-7 and ENiCrMo-3 by Gas Tungsten Arc Welding (GTAW) process. Investigations are carried out on the metallurgical and mechanical properties of AISI 304L weldments. Further, cyclic hot corrosion studies are performed on the various zones of the weldment in air oxidation for 50 cycles at 600 ^°C. Thermogravimetric data is collected at the end of every cycle and the weldments are characterized using XRD analysis.

Abstract: X-ray diffraction (XRD) is a versatile, non-destructive technique that reveals detailed information about the chemical composition and crystallographic structure of materials. In this work Ni-20Cr and Ni-50Cr coatings were deposited on two boiler steels namely T22 and SA 516 steel. The measurement of residual stresses of these cold sprayed coatings was done with the help of X-ray diffraction technique. This paper discussed the XRD study of the as-sprayed coatings. Further the XRD technique was used to study the uncoated and coated steels after cyclic exposure to air, molten salt [Na₂SO₄-60%V₂O₅], and actual boiler environments. The results obtained from the XRD analysis have been shown. The weight change results showed that the coated steels performed better than their uncoated counterparts which might be attributed to the formation of protective phases.

Abstract: The present investigation is an attempt to evaluate the hot corrosion behaviour of high velocity-oxy fuel (HVOF) sprayed Cr3C2-25 % NiCr coating on 310S stainless steel in an actual industrial environment of a coal fired boiler. The cyclic studies were performed in the super heater zone of a coal-fired boiler where the temperature was around 700±100C. Experiments were carried out for 3 cycles each of 500 hours duration followed by 1 hour cooling in air till room temperature. X-ray diffraction (XRD) analysis and field emission scanning electron microscope (FESEM, FEI, Quanta 200F Company) with EDAX Genesis software attachment were used to analyse the oxidation-erosion products. The Cr3C2-25wt% NiCr coated specimen showed good adherence to the 310S SS substrate with negligible microspalling of the scales. The Cr3C2-25wt % NiCr coating deposited on 310S stainless steel imparted better hot corrosion resistance than the uncoated one in the given environment.

Abstract: In this research work, an attempt has been made to investigate the gas tungsten arc welded Monel 400 plates using ENiCu-7 for its mechanical and corrosion properties. Microstructure examination reveals the coarse grain formation of Ni-Cu phase in the heat affected zone (HAZ) and well defined dendrites are observed in the weld region. Tensile tests showed that fracture occurred at the weld interface and the ultimate tensile strength of the Monel weldment is found to be 515 MPa. Furthermore hot corrosion studies were performed on the different zones (Weld, HAZ and Base metal) of Monel 400 exposed to the thin film of molten salt environment of Na2SO4 - 60% V2O5 at 600°C. It was found that corrosion was extremely severe on the fusion zone after exposed to 50 cycles. The corrosion products were characterized using the combined techniques of optical microscopy, XRD, SEM/EDX analysis

Abstract: In this study, NiCoCrAlY bond coat and two types of top coat including yttria stabilized zirconia (YSZ) and ceria and yttria stabilized zirconia (CYSZ) were deposited on IN 738LC by air plasma spraying (APS). Hot corrosion behavior of samples in 1000 °C was study using 55wt.%V2O5-45wt.%Na2SO4 corrosive salt. Characterization and analysis of results was done by employing field emission scanning electron microscope (FESEM) and x-ray diffractometry (XRD). Results ravealed that plasma sprayed CYSZ TBCs exhibited excellent hot corrosion resistance which was superior to that of YSZ TBCs due to strong acidity and high contents of stabilizer.

Abstract: This paper investigated the influence of filler materials such as E308L and ENiCu-7 utilized in the GTA welded AISI 304 with respect to mechanical and corrosion properties. It was found that E308L had shown better tensile strength and corrosion resistance as compared to ENiCu-7. A comparative analysis had been made on the different regions of the weldment subjected to cyclic air oxidation at 700°C. The corrosion products were examined using XRD and SEM/EDAX analysis.

Abstract: Oxidation and hot corrosion are serious problems in marine and power plants. Hence understanding the corrosion behavior of weldment at elevated temperatures has become the vital scientific investigation nowadays. Monel 400 is one of the widely used high temperature material that can obviate the problems. The objective of the present investigation is to study the mechanical properties and corrosion behaviour of gas tungsten arc welded Monel 400 plates subjected to air oxidation. It was observed from the tensile tests that fracture occurred at the weld region. In addition, cyclic air oxidation tests were performed on the different regions of welded Monel 400 at 700°C. It was found that corrosion was found to be extremely severe on the weld zone after exposed to 50 cycles. The corrosion products were characterized using the combined techniques of optical microscopy, XRD, SEM/EDAX analysis.

Abstract: In this work, an attempt was made to examine the microstructure changes on the gas tungsten arc welded AISI 304 subjected to hot corrosion in Na₂SO₄ + V₂O₅ (60%) at 700°C under cyclic conditions. It was found that welding of AISI 304 using E308L showed better corrosion resistance and tensile strength as compared to ENiCu-7 filler wire. The corrosion products were analyzed using SEM/EDAX and XRD.