Papers by Keyword: Cavitation Erosion

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Authors: Ashish Selokar, D.B. Goel, Ujjwal Prakash
Abstract: Abstract: Hydroturbine blades in hydroelectric power plants are subjected to erosion. Currently these blades are made of 13/4 martensitic stainless steel (ASTM grade A743). This steel suffers from several maintenance and welding related problems. Nitronic steels are being considered as an alternative to martensitic stainless steels since they have good weldability. In present work, erosive behaviour of 13/4 Martensitic and Nitrogen alloyed austenitic stainless steel (23/8N steel) has been studied. Cavitation erosion tests were carried out in distilled water at 20 KHz frequency at constant amplitude. Microstructure of eroded surface, mechanical properties and erosion rate were characterized. It was observed that 23/8N steel possesses excellent resistance to erosion in comparison to 13/4 martensitic steels. 23/8N steel showed good hardness coupled with high tensile toughness and work hardening ability, leading to improved erosion resistance.
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Authors: J. Madadnia, Dinesh K. Shanmugam, Thai Nguyen, Jun Wang
Abstract: Current jet cutting systems experience severe nozzle erosion and associated maintenance and downtime costs. An experimental investigation was conducted to qualitatively and quantitatively analyse the generation of cavitation in a high pressure water jet cutting system, and to characterise cavitation induced accelerated surface erosion by slurries. The analysis of surface morphology indicates that the shearing induced by cavitation played a major role in the erosion process. The results promise a feasible solution to reduce nozzle wear, and to enhance material removal in the jet cutting process.
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Authors: Hassan Jayaraj Amarendra, Gajanan P. Chaudhari, S.K. Nath
Abstract: In harnessing clean and renewable energy sources water turbines represent a significant portion of the power generation worldwide. Because of erosion, repair and maintenance of hydraulic turbines is a difficult problem. Material removal in hydraulic turbine components may occur either by particle erosion or cavitation erosion or by their combined action. Many ASTM standard and non standard test rigs are aimed at specific tests, like solid particle erosion, cavitation erosion. To simulate the real conditions in a laboratory setup, a novel method is employed to combine the effect of cavitation erosion and slurry erosion in the slurry pot tester. Triangular prismatic cavitation inducers are used in the conventional slurry pot tester. The aluminum test specimens are investigated in the slurry pot tester. A wide variation in material loss was noted under different exposure conditions. The maximum material loss is ascribed to combined effects of solid particle erosion and cavitation erosion.
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Authors: Chang Jun Liu, Jun Ma, Xiao Qiang Li, Yong Su
Abstract: Throttling pipelines are adopted to improve their cavitation erosion resistance, while there often exists cavitation erosion, large energy loss and big noise in throttling pipelines. In this study, the three-dimensional (3D) model of the secondary throttling pipeline was constructed according to the actual structure and parameters. It has been calculated that compared to the ordinary throttling pipeline, the secondary throttling pipeline makes the maximum velocity decreased from 19.827 to 19.168 m/s, and the minimum negative pressure increased from-2.02 to-1.77 MPa. The results is significant for choosing and designing the throttling pipelines.
302
Authors: Marek Szkodo
Abstract: The laser surface alloying of 18/8 stainless steel with Mn, was carried out by 6 kW cw CO2 laser. The microstructure, chemical composition and phase identification of the modified layer were examined using scanning electron microscopy, energy dispersive X-ray spectroscopy and Xray diffractometry, respectively. Cavitation behavior of produced layers was investigated in a rotating disc facility. Cavitation properties of laser-processed steel were calculated in the initial stage of erosion, on the surface of about 4 mm2, on which cavitation intensity was constant. As a property characterizing the cavitation erosion resistance of materials was proposed for the depth of strain hardening. It was found that presence of manganese in the amount of 7.31% causes the highest increase hardness after alloying and the lowest depth of strain hardening due to cavitation loading.
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Authors: Nadia Potoceanu, Marian Dumitru Nedeloni, Daniel Chirus, Danut Florea
Abstract: This paper presents the cavitation erosion research of the antifriction alloy YSn83 regarding on its behavior in laboratory. The antifriction alloy YSn83 is not subject to cavitation erosion in its practical applications, as is happening in reality at the materials used in hydraulic turbines, valves, piping; but the experimental tests for this material, highlight the laboratory research on its behavior by means of images and graphs in this paper. The laboratory tests were performed in accordance with the standards G32-92 (Standard Method of Vibratory Cavitation Erosion Test) and G32-10 (Standard Test Method for Cavitation Erosion Using Vibratory Apparatus).
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Authors: Zhi Hua He, Yu Ping Wu, Hong Bin Sun, Yuan Zheng, Yu Dong, Sheng Hong, Gai Ye Li
Abstract: In order to increase cavitation erosion resistance of fluid machinery, an iron-based coating was prepared by high velocity arc spraying (HVAS) on the surface of 1Cr18Ni9Ti stainless steel. The microstructure and performance were investigated respectively by optical microscope (OM), X-ray diffraction (XRD), scanning electron microscope (SEM), Vickers hardness and vibratory cavitation apparatus. The results indicated that the coating had the higher hardness (8.67GPa) and the finer structure than ZG230-450 (1.86GPa) used actual in water conservancy. Compared with ZG230-450, cavitation erosion resistance of the coating was better, and the coating presented flakiness stripping mode. The results indicated that the HVAS is a promising method to prepare the cavitation resistance coating.
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Authors: Dorian Nedelcu, Marian Dumitru Nedeloni, Cinca Ionel Lupinca
Abstract: The paper presents ample researches on cavitation erosion of two charges of stainless steel type X3CrNi13-4 on a cavitation stand, through the stationary specimen method. The results of the experimental trials are highlighted in tables and in graphics regarding the reproduction of mass losses and the cavitation erosion rate according to time. The images of the microstructures before the cavitation test and the macrostructures after the cavitation test of the two charges of stainless steel type X3CrNi13-4 are also presented in this paper.
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Authors: Marek Szkodo
Abstract: This work presents investigations of cavitation properties of different austenitic microstructures formed by laser beam machining of X5CrNi18-10 and C45 steels. X5CrNi18-10 steel was alloyed with TiC and Mn powders and surface layer of C45 steel was enriched with Ni, Mn, Cr and Nb. For alloying the cw CO2 laser beam was used as a power source. Cavitation behaviour of produced layers was investigated in a rotating disc facility. The results reveal different susceptibility to plastic deformation and strain hardening degree of surface in the early stage of cavitation erosion.
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Authors: Marek Szkodo, Artur Sitko, Maria Gazda
Abstract: This paper presents investigation of cavitation erosion resistance of nitrided austenitic stainless steel X5CrNi18-10. The diffusion layers were produced by using different parameters of reactive atmosphere (N2:H2). The microstructure, chemical composition and phase identification of the modified layer were examined using scanning electron microscopy, glow-discharge optical emission spectrometer and X-ray diffractometry, respectively. Cavitation erosion resistance of produced surface layers was investigated in a rotating disc facility. As a property characterizing the cavitation erosion resistance of manufactured surface layers were proposed incubation period and mass loss after 330 min of cavitation test. It was found that cavitation erosion resistance of modified surface layers is lower than reference material (not treated X5CrNi18-10 stainless steel).
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