Evaluation of Advanced Wire-EDM Capabilities for the Manufacture of Fir Tree Slots in Inconel 718

Klocke, Fritz; Welling, D.; Klink, Andreas; Veselovac, D.; Nöthe, Tobias; Pérez, Rebeca

doi:10.1016/j.procir.2014.03.039

Cited by 90 publications

(62 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In recent days, many attempts have been made to improve the machinability of these materials (especially Inconel 718) more effectively via nonconventional processes (such as electric discharge machining (EDM) [34,32], abrasive waterjet machining (AWJM) [35], electrochemical machining (ECM) [27,36]), or by the use of external energy assisting the conventional machining (like LAM [37,38,31], vibrationassisted machining (VAM) [39], plasma-enhanced machining (PEM) [40]). Different machining processes widely used for the processing of Inconel 718 are listed in Table 1 showing the advantages and shortfalls of each process.…”

Section: Machining Of Inconel 718mentioning

confidence: 99%

A comparison of laser beam machining of micro-channels under dry and wet mediums

Darwish

Ahmed

Alahmari

et al. 2015

Int J Adv Manuf Technol

View full text Add to dashboard Cite

Micro-channels have been fabricated in nickelbased superalloy (Inconel 718) through laser beam machining (LBM). Two machining mediums are employed: dry and wet medium. Under the dry medium, laser beam passes through air prior to strike with target surface while under wet medium, the laser beam first travels through a layer of distilled water and reaches the substrate after. For both the machining environments, effects of laser power, pulse repetition rate, and laser scan speed on machined channels' width, depth, and taperness are investigated. A comparison of parametric effects on machined channels' profiles has been carried out for the said machining conditions. The results reveal that LBM under distilled water is more productive than LBM under air environment. In one step, wet machining conditions allow to generate a set of two microchannels, and dry conditions generate one micro-channel. Further, to achieve the optimum dimensions of micro-channels, the appropriate level of each of the investigated laser parameter is proposed.

show abstract

Section: Machining Of Inconel 718mentioning

confidence: 99%

A comparison of laser beam machining of micro-channels under dry and wet mediums

Darwish

Ahmed

Alahmari

et al. 2015

Int J Adv Manuf Technol

View full text Add to dashboard Cite

show abstract

“…The giant heat generation, as the nature of the process, causes melting and even evaporation of the surface material, and the white layer is formed during subsequent rapid cooling [37,41,70]. Dependent on the material to be machined and the machining process specifically employed, the underlying mechanism for white layer formation changes.…”

Section: Surface Metallurgymentioning

confidence: 99%

Surface Integrity and Fatigue Performance of Nickel-based Superalloys

Chen¹

View full text Add to dashboard Cite

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...

show abstract

“…derived a set of EDM parameters optimizing the surface integrity for the manufacturing of nickel-based alloy turbine blades [8]. With this set of parameters negative surface modifications are reduced to a minimum [6]. Moreover, in order to further improve surface integrity LAUWERS ET AL.…”

Section: Wire Electrical Discharge Machiningmentioning

confidence: 99%

“…Thus, workpieces made of Inconel718, e.g. fir tree slots [6], are alternatively manufactured using wire electrical discharge machining (wire EDM). Wire EDM is a manufacturing process where workpiece material is removed by a series of recurring current discharges.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the surface integrity and fatigue strength of Inconel718 after wire EDM and machine hammer peening

et al. 2015

Self Cite

View full text Add to dashboard Cite

Highly stressed turbine blades made of Inconel718 (DIN NiCr19NbMo (2.4668); ASTM B637; UNS N07718) have to satisfy stringent requirements regarding durability and reliability. The impact of surface integrity on the fatigue strength of the workpiece material has proven to be of significant importance. An optimization of the surface integrity after wire EDM of Inconel718 can be achieved using the surface finishing process machine hammer peening. Machine hammer peening is an incremental forming process which has the potential to induce residual compressive stresses and strain hardening while smoothing surface asperities. As the effect of machine hammer peening on surface integrity has not yet been completely investigated, this paper deals with its description and modeling of the unknown impact of machine hammer peening on the fatigue strength of Inconel718. Wire EDM and machine hammer peening parameters maximizing the fatigue strength are presented. Experimental measurements are performed to quantify the surface integrity, especially surface roughness, compressive residual stresses and strain hardening, after wire EDM and subsequent machine hammer peening. The evaluation of the effect of surface integrity on the fatigue strength is carried out using a bending fatigue strength testing machine. Additionally, a finite element model is developed to analyze the surface integrity under load and to reveal the effects of difficult-to-measure properties on the fatigue strength. Based on the new knowledge gained during this work, a model to predict the fatigue strength using similitude theory is presented. Along with the previously analyzed correlations between surface integrity and fatigue strength, this allows a constructive setting of machine hammer peening parameters. Thereby, a significant new contribution to knowledge about the influence of machine hammer peening on surface integrity and fatigue strength of Inconel718 is made. The presented approach can be easily transferred to other materials and workpiece geometries

show abstract

Evaluation of Advanced Wire-EDM Capabilities for the Manufacture of Fir Tree Slots in Inconel 718

Cited by 90 publications

References 12 publications

A comparison of laser beam machining of micro-channels under dry and wet mediums

A comparison of laser beam machining of micro-channels under dry and wet mediums

Surface Integrity and Fatigue Performance of Nickel-based Superalloys

Investigation of the surface integrity and fatigue strength of Inconel718 after wire EDM and machine hammer peening

Contact Info

Product

Resources

About