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dc.contributor.authorNewton, Thomas Russellen_US
dc.date.accessioned2008-06-10T20:38:26Z
dc.date.available2008-06-10T20:38:26Z
dc.date.issued2008-02-15en_US
dc.identifier.urihttp://hdl.handle.net/1853/22580
dc.description.abstractInconel 718 is a high nickel content superalloy possessing high strength at elevated temperatures and resistance to oxidation and corrosion. The non-traditional manufacturing process of wire-electrical discharge machining (EDM) possesses many advantages over traditional machining during the manufacture of Inconel 718 parts. However, certain detrimental effects are also present. The top layer of the machined surface is melted and resolidified to form what is known as the recast layer. This layer demonstrates microstructural differences from the bulk workpiece, resulting in altered material properties. An experimental investigation was conducted to determine the main machining parameters which contribute to recast layer formation in wire-EDM of Inconel 718. It was found that average recast layer thickness increased with energy per spark, peak discharge current, current pulse duration, and open-voltage time and decreased with sparking frequency and table feed rate. Over the range of parameters tested, the recast layer was observed to be between 5 and 10 μm in average thickness, although highly variable in nature. Surface roughness of the cut parts showed an increase with energy per spark. Electron Probe Microanalysis (EPMA) revealed the recast layer to be alloyed with elements from the wire electrode. X-ray diffraction testing showed the residual tensile stresses evident near the cut surface to decrease with energy per spark. Additionally, nano-indentation hardness testing indicated that the recast layer is reduced in hardness and elastic modulus compared to the bulk material. Vibratory tumbling was found to be a moderately effective post-processing tool for recast layer removal when using pre-formed ceramic abrasive media or fine grained aluminum oxide.en_US
dc.publisherGeorgia Institute of Technologyen_US
dc.subjectNano-indentation hardness testingen_US
dc.subjectX-ray diffractionen_US
dc.subjectElectron probe microanalyzeren_US
dc.subjectScanning electron microscopeen_US
dc.subjectXRDen_US
dc.subjectEPMAen_US
dc.subjectSEMen_US
dc.subject.lcshHeat resistant alloys
dc.subject.lcshInconel
dc.subject.lcshMachining
dc.subject.lcshElectric metal-cutting
dc.titleInvestigation of the effect of process parameters on the formation of recast layer in wire-EDM of Inconel 718en_US
dc.typeThesisen_US
dc.description.degreeM.S.en_US
dc.contributor.departmentMechanical Engineeringen_US
dc.description.advisorCommittee Chair: Melkote, Shreyes; Committee Member: Danyluk, Steven; Committee Member: Steven Liangen_US


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