Effect of Pressure and Temperature on Densification in Electric Field-Assisted Sintering of Inconel 718 Superalloy

Electric field-assisted sintering has ubiquitous merits over conventional sintering technology for the fabrication of difficult-to-deform materials. To investigate the effect of sintering pressure and temperature on the densification of Inconel 718 superalloy, a numerical simulation model was established based on the Fleck-Kuhn-McMeeking (FKM) and Gurson-Tvergaard-Needleman (GTN) models, which covers a wide range of porosity. At a sintering pressure below 50 MPa or a sintering temperature below 950 °C, the average porosity of the sintered superalloy is over 0.17 with low densification. Under a pressure above 110 MPa and a temperature above 1250 °C, the sintered superalloy quickly completes densification and enters the plastic yield stage, making it difficult to control the sintering process. When the pressure is above 70 MPa while the temperature exceeds 1150 °C, the average porosity is 0.11, with little fall when the pressure or temperature rises. The experimental results indicated that the relative density of the sintered superalloy under 70 MPa and 1150 °C is 94.46%, and the proportion of the grain size below 10 μm is 73%. In addition, the yield strength of the sintered sample is 512 MPa, the compressive strength comes to 1260 MPa when the strain is over 0.8, and the microhardness is 395 Hv, demonstrating a better mechanical property than the conventional superalloy.

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Investigation of the Machinability of the Inconel 718 Superalloy during the Electrical Discharge Drilling Process

Materials ◽

10.3390/ma13153392 ◽

2020 ◽

Vol 13 (15) ◽

pp. 3392 ◽

Cited By ~ 1

Author(s):

Magdalena Machno

Keyword(s):

Process Parameters ◽

Inconel 718 ◽

Electrical Discharge ◽

Current Amplitude ◽

Aviation Industry ◽

Wide Range ◽

Inconel 718 Superalloy ◽

Side Gap ◽

The Impact ◽

Edm Process

The properties of the Inconel 718 superalloy are used in the manufacturing of aircraft components; its properties, including high hardness and toughness, cause machining difficulties when using the conventional method. To circumvent this, non-conventional techniques are used, among which electrical discharge machining (EDM) is a good alternative. However, the nature of removing material using the EDM process causes the thermophysical properties of Inconel 718 to hinder its machinability; thus, a more extensive analysis of the influence of these properties on the EDM process, and a machinability analysis of this material in a wider range, using more process parameters, are required. In this study, we investigated the drilling of micro-holes into the Inconel 718 superalloy using the EDM process. An experiment was conducted to evaluate the impact of five process parameters with a wide range of values (open voltage, time of the impulse, current amplitude, the inlet dielectric fluid pressure, and tube electrode rotation) on the process’s performance (drilling speed, linear tool wear, the side gap thickness, and the aspect ratio of holes). The analysis shows that the thermal conductivity of this superalloy significantly influences the effective drilling of holes. The combination of a higher current amplitude (I ≥ 3.99 A) with an extended pulse time (ton ≥ 550 µs) can provide a satisfactory hole accuracy (side gap thickness ≤ 100 µm), homogeneity of the hole entrance edge without re-solidified material, and a depth-to-diameter ratio of about 19. Obtaining a high dimensional shape accuracy of holes has an enormous effect on their usability in the structure of the components in the aviation industry.

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Thermomechanical behavior of laser metal deposited Inconel 718 superalloy over a wide range of temperature and strain rate: Testing and constitutive modeling

Mechanics of Materials ◽

10.1016/j.mechmat.2019.04.024 ◽

2019 ◽

Vol 135 ◽

pp. 13-25 ◽

Cited By ~ 8

Author(s):

Kangbo Yuan ◽

Weiguo Guo ◽

Penghui Li ◽

Yang Zhang ◽

Xiaolong Li ◽

...

Keyword(s):

Strain Rate ◽

Constitutive Modeling ◽

Inconel 718 ◽

Thermomechanical Behavior ◽

Wide Range ◽

Rate Testing ◽

Inconel 718 Superalloy

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Residual Stress Enhancement in 3D Printed Inconel 718 Superalloy Treated by Ultrasonic Nano-Crystal Surface Modification

Volume 2: Additive Manufacturing; Materials ◽

10.1115/msec2017-2918 ◽

2017 ◽

Author(s):

Kuldeep Singh Sidhu ◽

Jing Shi ◽

Vijay K. Vasudevan ◽

Seetha Ramaiah Mannava

Keyword(s):

Heat Treatment ◽

Residual Stress ◽

Surface Modification ◽

Residual Stresses ◽

Inconel 718 ◽

Crystal Surface ◽

High Temperature Strength ◽

Heat Treated ◽

Wide Range ◽

Inconel 718 Superalloy

Inconel 718 (IN718) is a nickel based Ni-Cr-Fe super alloy. It has a unique set of properties such as good workability, corrosion resistance, high temperature strength, favorable weldability and excellent manufacturability. Due to its wide range of applications, IN718 is an alloy of great interest for many industries. Meanwhile, additive manufacturing assisted with laser has caught much interest from researchers and practitioners in the past three decades. In this study, IN718 alloy coupons are manufactured by selective laser melting (SLM) technique. The SLMed IN718 alloys are treated by ultrasonic nanocrystal surface modification (UNSM), and the residual stress distributions underneath the surfaces are measured. It is found that residual stress mostly tensile is induced while building the part by the SLM technique. The tensile stresses can be reduced to almost zero value by post heat treatment. Moreover, the heat treatment helps to homogenize the microstructure, and results in the increase in hardness. More importantly, it is observed that UNSM effectively induces compressive residual stresses in the as-built and heat-treated parts. The residual stresses of compressive nature in as built parts has depth of around 530 μm where as in heat treated parts has a depth of around 530μm.

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Effect of Electric Field Treatment on Vacancy of Inconel 718 Superalloy at 1073 K

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.409.769 ◽

2011 ◽

Vol 409 ◽

pp. 769-773 ◽

Cited By ~ 2

Author(s):

Yao Wang ◽

Lei Wang ◽

Xin Yu Zhang ◽

Yan Long Li ◽

Yang Liu ◽

...

Keyword(s):

Electric Field ◽

Positron Annihilation ◽

Inconel 718 ◽

Lattice Site ◽

Vacancy Concentration ◽

Three Dimensional ◽

Positron Annihilation Lifetime ◽

Normal Lattice ◽

Inconel 718 Superalloy ◽

Electric Field Treatment

Effect of electric field treatment with different intensities on vacancy of Inconel 718 aged at 1073 K was investigated. The positron annihilation lifetime (PAL) and corresponding concentration of vacancies were measured by positron annihilation technique. It was found that atomic vibration at lattice site can be promoted by an external electric field performed on Inconel 718 superalloy during aged at elevated temperature. Some atoms owing the higher vacancy formation energy or larger radius will jump out from the normal lattice sites and form defects, which is leading to the increase of PAL of monovacancy. Under continuous effect on electric field, monovacancies will transform to three-dimensional vacancies of lower energy and vacancy clusters. Moreover, the vacancy concentration of Inconel 718 superalloy can be improved evidently by electric field treatment, and the average PAL of vacancies can be up to 6.3% when the electric field intensity is up to 8 kV/cm, which is very useful for controlling the microstructures evolution and properties of the superalloy, such as solute redistribution and precipitations.

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Development of PEF extraction technology by Maguin

Sugar Industry ◽

10.36961/si17024 ◽

2015 ◽

pp. 758-760

Author(s):

Romain Delecourt ◽

Loïc Marsal

Keyword(s):

Sugar Beet ◽

Electric Field ◽

Pulsed Electric Field ◽

Extraction Technology ◽

Application System ◽

Wide Range ◽

Type Machine

Maguin (France) is still active in the application of pulsed electric field (PEF) technology. After having carried out successful tests on a 10 t/h pilot screw-type machine on sugar beet cossettes, a new application system based on a roller technology has been developed. This technology allows a wide range of application due to its flexibility with flowrates and materials. A variety of process schemes are proposed to ensure the best performance of the PEF technology.

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Study of ultrasonic vibration–assisted thread turning of Inconel 718 superalloy

Advances in Mechanical Engineering ◽

10.1177/1687814019883772 ◽

2019 ◽

Vol 11 (10) ◽

pp. 168781401988377

Author(s):

Yu He ◽

Zhongming Zhou ◽

Ping Zou ◽

Xiaogang Gao ◽

Kornel F Ehmann

Keyword(s):

Surface Quality ◽

Ultrasonic Vibration ◽

Inconel 718 ◽

Gas Turbines ◽

Tool Path ◽

Machining Parameters ◽

Thread Cutting ◽

Workpiece Surface ◽

Inconel 718 Superalloy ◽

The Relationship

With excellent properties, high-temperature superalloys have become the main application materials for aircraft engines, gas turbines, and many other devices. However, superalloys are typically difficult to machine, especially for the thread cutting. In this article, an ultrasonic vibration–assisted turning system is proposed for thread cutting operations in superalloys. A theoretical analysis of ultrasonic vibration–assisted thread cutting is carried out. An ultrasonic vibration–assisted system was integrated into a standard lathe to demonstrate thread turning in Inconel 718 superalloy. The influence of ultrasonic vibration–assisted machining on workpiece surface quality, chip shape, and tool wear was analyzed. The relationship between machining parameters and ultrasonic vibration–assisted processing performance was also explored. By analyzing the motion relationship between tool path and workpiece surface, the reasons for improved workpiece surface quality by ultrasonic vibration–assisted machining were explained.

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