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Inconel alloys are a family of nickel-based superalloys that consist of a wide range of compositions and properties. Inconel 718 is one of superalloys used in the aerospace industry due to its good mechanical properties; such as high corrosion and creep resistance at high temperatures. Despite these advantages, Inconel 718 is among the most difficult materials to be machined. In this paper, a finite element model for orthogonal machining of Inconel 718 was developed in order to investigate the effective parameters on the force, temperature and chip morphology. The plastic behavior of material was simulated with Johnson-cook material model, and constant shear friction factor (m) is used to model the friction between chip and tool interface. Then, the simulation results were compared with experimental values with which a good agreement was found between them. After validating the simulation results, the effect of coefficient friction, cutting speed and rake angle, on the cutting edge temperature, force on the tool and chip morphology was achieved by using design of experiments (DOE) method. According to the results, feedrate (with 30% contribution) and friction coefficient (with 19% contribution) have the greatest impact on the force on the tool. Rake angle (with 31% contribution), cutting speed (with 21% contribution) and feedrate (with 20% contribution) are the most effective parameters on the cutting edge temperature. The friction coefficient and feedrate (both with 25% contribution) have the greatest impact on the chip geometry.

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In this paper, transient liquid phase (TLP) bonding process between Inconel 718 alloy and Inconel 600 alloy using a BNi-2 interlayer with 50 μm thickness was investigated. Transient liquid phase bonding process was performed at 1050 °C for 5, 25 and 45 min. Microstructure evaluation was carried out through optical microscopy, field emission scanning electron microscopy (FE-SEM). Also, bonding shear strength was measured. The results showed that the joint microstructure was formed of three zones including isothermal solidification zone (ISZ), thermal solidification zone (ASZ) and diffusion affected zone (DAZ). At the time of 5 min, boride intermetallic compounds in thermal solidification zone were formed. Isothermal solidification was completed and thermal solidification zone was vanished by increasing the bonding time from 5 to 45 min. Diffusion affected zone of the Inconel 718 alloy was persistent and expanded by increasing the time and diffusion of B element to parent metals, but this region in Inconel 600 alloy was vanished and the homogenization process was occurred by increasing the bonding time. Also, because of remove of boride intermetallic compounds, changes of hardness in joint region were more smoothly and the hardness value of joint region was about 280 HV. The results of shear strength showed that the bonding strength was increased from 250 MPa to 410 MPa with increasing the bonding time from 5 to 45 min, respectively.

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In this article, the effect of optimal selection of vibration and cutting parameters on cutting forces in the machining process with ultrasonic vibration assistance has been investigated and the results have been compared in two modes of conventional machining and of ultrasonic vibration assisted machining. In the investigation of the effect of ultrasonic vibration assistance on the machining process, analyzes have been carried out in different cutting speeds, and the effect of changing the cutting speed in relation to the tool's oscillation speed has been investigated. Finite element modeling and simulation has been done with DEFORM finite element software. The results show that the application of ultrasonic vibration in the machining process leads to the reduction of tangential and axial cutting and the reduction of heat resulting from the cutting process. By examining the results, it was found that in the machining process with ultrasonic vibration assistance, when the cutting speed is at least 30% lower than the vibration speed of the tool tip, the process has a favorable efficiency, and the favorable effects of applying ultrasonic vibration on the process include reducing shear forces, reducing the heat generated From cutting, reducing the friction coefficient between the tool and the workpiece, helping to improve the chip flow, etc.

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In this paper, by performing heat treatment on IN718 superalloy specimens that are manufactured by additive manufacturing method, the purpose is to investigate the experimental and analytical behavior of stress relaxation. The 3D printed specimens were made by the selective laser melting (SLM) method and after homogenization and solution heat treatment; they were subjected to stress relaxation at the temperature of 650 °C with an initial strain of 1.1% and 2.1% for 8 hours. Due to investigate the effect of strain changes on the stress relaxation, the stress relaxation limit diagram, which is 119.55 and 514.35 MPa for strains of 1.1% and 2.1%, respectively, shows that the stress relaxation limit increases with the increase of the initial strain. Furthermore, by examining the stress relaxation behavior in the experimental specimens, it was found that the amount and slope of the relaxation curve is higher in the specimen with a strain of 2.1%. In the analytical study, the creep constitute equations were also used to investigate the stress relaxation behavior, which by checking the presented comparative curves, by recording the error amount of 2.17% and 3.85% for the strains of 1.1% and 2.1%, respectively, the result of the comparison indicates a good agreement between the analytical results and the experimental curves.

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Inconel 718 superalloy is widely used in various industries due to its excellent high-temperature properties. The production of components made from Inconel 718 superalloy through the Selective Laser Melting (SLM) method enables the fabrication of parts with complex geometries. Therefore, improving the mechanical properties of parts produced by SLM using secondary strengthening processes is of great importance. This study investigates the effect of cold pre-strain on the tensile and compressive strength of Inconel 718 superalloy samples produced by SLM. The test specimens were produced by the SLM method and subjected to single-stage (5%-15%-30%) and two-stage (4%-12%-16%) loading. To examine the impact of initial loading on mechanical properties, tensile, compression, and hardness tests were performed, and the microstructure behavior was analyzed using an optical microscope. The results indicate that the yield strength and ultimate tensile strength of the Inconel 718 superalloy in the Y-axis (XY plane) increased by 31.8% and 11.6%, respectively, after applying a 30% initial strain along the Z-axis. The compressive yield strength of Inconel 718 superalloy increased by 79.3% in the Z-direction with a 30% pre-strain. In other words, applying pre-strain along the Z-axis affects the compressive strength in the XZ plane as the principal strain and the tensile strength in the XY plane as the shear strain. Increasing pre-strain to 30% has a minimal effect on the hardness properties of Inconel 718 superalloy. The results from the two-stage loading process indicate an enhancement in strength with the increase in the number of loading stages, attributed to the work-hardening phenomenon