Cyclic oxidation and hot corrosion performance of direct metal laser sintered and wrought alloy 718 at 800°C in air and molten salts containing Na2SO4, V2O5 and NaCl
S. Muthu, Dhinakaran Veeman, Shiladithya Paul, M. Prem kumar
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引用次数: 0
Abstract
ABSTRACT The main aim of this research work is to investigate the high-temperature cyclic corrosion performance of the wrought and direct metal laser sintered (DMLS) alloy 718 in the air and molten salts NaCl-90%Na2SO4 and three salt mixture (3SM) Na2SO4-10%V2O5-10%NaCl atmosphere for 120 h at 800°C. The microstructure of the wrought and DMLS alloy illustrated the austenitic and dendrite structure. Scanning electron microscope (SEM) and X-ray diffraction (XRD) were used to evaluate the structure and phase constitutions of the scale. Visual and microstructural evaluation of the alloy post-exposure indicates that corrosion is more prevalent in molten salt conditions, when compared to air, and Cl-species induced the active oxidation in molten salt. The oxide film development and damage mechanism were detailed and explained by a cross-sectional investigation. Significant spalling and sputtering were also noticed in the S3 salt mixture. This might be attributed to the rapid formation of oxide scales by vanadate, followed by dissolution of the oxide in molten sulphate and chloride. The results divulged that both AM-built and wrought alloy exhibited the similar corrosion properties and both the alloys were undergone severe degradation in MS condition. Highlights Alloy 718 was fabricated successfully by the direct metal laser sintering (DMLS) method. Cyclic high-temperature oxidation and corrosion of the alloy were studied at 800°C. The oxidised sample exhibits a lower weight gain with no damage. Due to chlorination and sulfidation, the corroded samples exhibited more oxidation and susceptible. GRAPHICAL ABSTRACT
期刊介绍:
Corrosion Engineering, Science and Technology provides broad international coverage of research and practice in corrosion processes and corrosion control. Peer-reviewed contributions address all aspects of corrosion engineering and corrosion science; there is strong emphasis on effective design and materials selection to combat corrosion and the journal carries failure case studies to further knowledge in these areas.