Abstract
Inconel 718 superalloy is widely used in many applications requiring higher material strength. Electro Discharge Machining (EDM) is a popular process for machining this superalloy owing to its high thermal resistance and high hardness. In the current work, electro discharge machining was carried out on Inconel 718 using 99.9% pure copper as an electrode with tubular cross section. Thirty two sets of machining trials were conducted as per the design of experiments using the central composite design (CCD) method. The effect of process parameters like pulse current, duty factor, sensitivity, gap control and dielectric flushing pressure on the formation of recast layer, heat affected zone and spattered EDM surface was analysed. Machined samples were characterized for few surface integrity factors through field emission scanning electron microscope (FE-SEM), and surface roughness measurement. The microstructures of the EDM processed Inconel 718 reveal formations of a white layer on the machined surface. It was observed that the process parameters, base material properties and white layer composition have significant influence on crack formation and its propagation. Different modes of crack propagation were identified. Surfacial and vertical cracking were predominantly observed in the recast layer; most of the vertical cracks were found to have progressed till the end of the recast layer. The interferential zone acted as a barrier to crack propagation due to the non-homogeneities of metallurgical phases. Crack propagation was observed varying significantly with pulse current and duty factor.
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© 2010 Springer-Verlag London Limited
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Rajesha, S., Sharma, A., Kumar, P. (2010). Some Aspects of Surface Integrity Study of Electro Discharge Machined Inconel 718. In: Hinduja, S., Li, L. (eds) Proceedings of the 36th International MATADOR Conference. Springer, London. https://doi.org/10.1007/978-1-84996-432-6_98
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DOI: https://doi.org/10.1007/978-1-84996-432-6_98
Publisher Name: Springer, London
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Online ISBN: 978-1-84996-432-6
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