Surface and Sub‐Surface Quality of Steel after EDM

Bleys, Philip; Kruth, Jean‐Pierre; Lauwers, Bert; Schacht, Benny; Balasubramanian, V.; Froyen, Ludo; Humbeeck, Jan Van

doi:10.1002/adem.200500211

Cited by 90 publications

(43 citation statements)

References 12 publications

(16 reference statements)

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“…Cusanelli et al [13] investigated the microstructure of the recast layer produced by EDM using kerosene as working fluid. Bleys et al [14] studied the influence of EDM on surface and subsurface quality in the manufacturing of mold and tool steel. Lee et al [15] analyzed the EDM machining of D2 and H13 tool steels and investigated the relationship between EDM parameters and surface cracks by using a full factorial design.…”

Section: Introductionmentioning

confidence: 99%

Modeling and experimental study on breakdown voltage (BV) in low speed wire electrical discharge machining (LS-WEDM) of Ti-6Al-4V

Gong

Yao

Cheng

et al. 2016

Int J Adv Manuf Technol

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In this study, the breakdown voltage behavior in low speed wire electrical discharge machining (LS-WEDM) of Ti-6Al-4V (TC4) in the deionized water is investigated. Firstly, the electric field distortion caused by impurity particles including TC4 or brass metal and bubbles is investigated. And then the breakdown voltage model of TC4 machined by LS-WEDM is established and the experimental verification result indicates that the model predicting results conforms to the actual processing and could be well follow experimental results. Second, the influence of breakdown voltage on surface roughness and kerf width has been revealed, it can be found that the kerf width decreases, and the surface roughness increases as breakdown voltage increased. Besides, the voids become bigger and the surface cracks become deeper and wider with the breakdown voltage increased based on analysis of experiment results but for microcracks distributed on spherical or irregular attachments are not influenced by breakdown voltage due to their randomness. Meanwhile, the transparent bubbles of diameter of 400 nm can be observed near the droplet on the machined surface and its major composing element is oxygen. Finally, internal voids can be found in the joint of deterioration layer and the substrate which will make the combination of deterioration layer and the substrate not strong and easy to fall off.

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Section: Introductionmentioning

confidence: 99%

Modeling and experimental study on breakdown voltage (BV) in low speed wire electrical discharge machining (LS-WEDM) of Ti-6Al-4V

Gong

Yao

Cheng

et al. 2016

Int J Adv Manuf Technol

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“…Therefore, great efforts have been dedicated to annihilate white layers in order to obtain a high resistance to fatigue crack initiation. This is particularly the case on the machined surface produced by EDM [36,38,39,[109][110][111].…”

Section: Crack Initiationmentioning

confidence: 99%

Surface Integrity and Fatigue Performance of Nickel-based Superalloys

Chen¹

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Gas turbines are widely used in e.g., power generation, and aero-industries. Due to global warming, the demand for more efficient gas turbines has increased. A way to achieve this is by increasing the operating temperature of gas turbines. Therefore, nickel-based superalloys have been developed to withstand these extreme temperatures and loads, especially in the hot sections.Today, the way of operating land-based gas turbines is changing. Instead of running for long periods of time, the operation is becoming more flexible, with everincreasing cyclic loads and number of start and stop cycles. To handle the increased stress and cycles, component resistance to fatigue failure needs to be improved.Surface integrity is critical to fatigue performance, since fatigue cracks are normally initiated at surfaces. Nickel-based superalloys are difficult-to-machine materials, primarily due to their high strength, high tendency for work-hardening, and low thermal conductivity. The machining process changes the surface integrity of the alloys which can result in worse fatigue resistance.The work presented in this Ph.D. thesis was conducted in collaboration with Siemens Industrial Turbomachinery AB in Finspång, Sweden. Surface integrity changes which are induced during machining and their effects on fatigue performance have been studied on alloy Inconel 718. Inconel 718 is a widely-used nickel-based superalloy for high temperature applications in modern gas turbines.Broaching, milling, and wire electrical discharge machining, related to component manufacturing in turbo machinery industries, were included in this study. Surface irregularity and defects induced by machining provide preferential sites for fatigue crack initiation which influence the fatigue performance of the alloy. If compressive residual stresses are induced during machining, they benefit the fatigue life by retarding fatigue crack initiation away from surface regions. Shot peening was performed on machined Inconel 718, by which high compressive residual stresses are deliberately induced. It results in increased fatigue performance. The high iv temperatures in gas turbines generally deteriorate the surface integrity. For instance, recrystallization often occurs in the highly plastically-deformed surface layer. Microstructural degradation, in a form of α-Cr precipitates, have also been observed in the deformed surface and sub-surface microstructure when subjected to thermal exposure. Oxidation at elevated temperatures was found to degrade the surface integrity and thereby also the fatigue performance. Fatigue cracks are preferably initiated at oxidized surface carbides, if thermal exposure has been made prior to the test, and a reduced fatigue life is often obtained. It is even worse when high temperatures relax the beneficial compressive residual stresses induced by shotpeening and thereby lowering the fatigue resistance. This increases the interest for research regarding how to optimize the shot peening process in order to enhance the thermal stability o...

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“…The surface texture after EDM is characterized by the typical discharge craters. This thermally influenced zone in EDM generally consists of several layers, as described in [15]. At the top a molten and resolidified layer is observed, also called the "white layer" or "recast layer".…”

Section: Methodsmentioning

confidence: 99%

“…A smaller rim zone is often associated with reduced residual tensile stresses, thus also reducing the negative influence on service life of a manufactured part or tool. A detailed study of the properties of surface layers after EDM-milling can be found in [15].…”

Section: Fig 4: Sem Image Of a Surface Manufactured By Edm-milling Amentioning

confidence: 99%

A Reliable Tool for the Improvement of Micro Powder Injection Moulds Made of Steel

et al. 2008

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Micro powder injection moulding (μPIM) is a common technique for an economic large‐scale production of micro parts. To ensure a long service life a high wear resistance is required which can better be fulfilled by moulds made of steel than by those made of brass. In this study the focus will be on the development of specific residual stress states at and below the surface of a mechanically processed Toolox 44 sample.

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Surface and Sub‐Surface Quality of Steel after EDM

Cited by 90 publications

References 12 publications

Modeling and experimental study on breakdown voltage (BV) in low speed wire electrical discharge machining (LS-WEDM) of Ti-6Al-4V

Modeling and experimental study on breakdown voltage (BV) in low speed wire electrical discharge machining (LS-WEDM) of Ti-6Al-4V

Surface Integrity and Fatigue Performance of Nickel-based Superalloys

A Reliable Tool for the Improvement of Micro Powder Injection Moulds Made of Steel

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