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Forming and Fracture Limit Diagrams of Inconel 718 Alloy at Elevated Temperatures
Published in Kakandikar Ganesh Marotrao, Anupam Agrawal, D. Ravi Kumar, Metal Forming Processes, 2023
Gauri Mahalle, Nitin Kotkunde, Amit Kumar Gupta, Swadesh Kumar Singh
It is important to discuss the fracture location of specimens (S1, S2, and S3) is observed slightly away from the dome apex. High friction coefficient during warm stretching test might be one of possible reasons. Because of friction between workpiece and a tool a significant effect was observed on forming load, die wear, component surface finish, and material deformation. If the friction coefficient controlled properly, it will generate shear stresses necessary to deform sheet workpiece to desired shape. If friction coefficient is not controlled properly, it might also cause occurrence of instability of sheet specimen fracture [18, 28]. In the present study, we used molybdenum-based lubricant (MOLYKOTE) to decrease friction between a tool and workpiece. During hot stretch forming, lubrication is more challenging as it may evaporate. Hence friction coefficient will be much higher than RT. As interface shear stress once exceeds flow shear stress, it may become pointless [10, 29]. Sheet contact region experience more tension because of frictionless contact between sheet specimen and punch than other sheet’s regions. As a result, fracturing occurs slightly away from dome apex. Also, strain-rate sensitivity and strain hardening of workpiece also influence fracture location. Variation in interface friction factor and strain-rate sensitivity may precede to substantial variations in predicted strain distribution [30]. Inconel has high value of strain-rate sensitivity and strain hardening exponent. Thus this might be another possible reason for side failure.
Flammability
Published in Asim Kumar Roy Choudhury, Flame Retardants for Textile Materials, 2020
The fire calorimeter is used by encasing a small sample in aluminum foil, wool and a retainer frame that is ignited below the exhaust hood. A conical heater is placed in between in order for materials to combust. The cone-shaped Inconel heating element provides a controllable radiant flux onto the sample, turning electricity into heat not unlike an electric toaster or oven. Inconel is a family of austenitic nickel-chromium-based superalloys or high-performance alloys. The austenitic is gamma-phase iron (γ-Fe), a metallic, nonmagnetic allotrope of iron or a solid solution of iron. The flammability of a sample can be characterized as a function of heat flux onto a sample. The conical heater is open in its center, allowing products of combustion to flow upwards into an exhaust duct.
Mechanics of Cooling Lubricating Fluid (CLF) through chip deformation in eco-friendly machining of Inconel 718
Published in Alka Mahajan, B.A. Modi, Parul Patel, Technology Drivers: Engine for Growth, 2018
Ganesh S. Kadam, Raju S. Pawade
Inconel 718, a nickel-based superalloy, is widely employed in the aerospace industry, marine equipment, nuclear reactors, petrochemical plants and food processing equipment due to its superior high-temperature strength, corrosion resistance and low thermal conductivity. However, Inconel 718 is known to be among the most difficult to cut materials due to properties that are responsible for poor machinability including rapid work hardening causing tool wear and poor thermal conductivity leading to high cutting temperatures (Pawade et al., 2007). Many problems caused during machining are due to heat generation and control over it for enhanced machining performance can be thus exercised by proper selection and application of Cooling and Lubricating Fluid (CLF). However, use of conventional CLFs cause problems such as high cost, pollution and hazards to the operator’s health, and thus, have urged researchers to seek suitable eco-friendly alternatives. Apart from surface integrity in turning of Inconel 718, few researchers have also focused their attention on chip formation aspects (Wang & Rajurkar, 2000; Ezugwu & Bonney, 2005; Su et al., 2007). Furthermore, few research investigations have also involved water vapor as a coolant and lubricant in machining of steels (Liu et al., 2005; Junyan et al., 2010), titanium alloy (Pawade et al., 2013) and Inconel 718 (Kadam & Pawade, 2017). Hence, keeping the literature gaps in view, the present paper discusses an experimental study to analyse the effect of machining and mainly water vapor parameters on lubrication and cooling aspects through chip deformation in high-speed turning of Inconel 718.
Grinding parameters prediction under different cooling environments using machine learning techniques
Published in Materials and Manufacturing Processes, 2023
Gorantala Sai Prashanth, Prithivirajan Sekar, Srikanth Bontha, A.S.S. Balan
Inconel is a nickel-based heat-resistant alloy widely used in the automotive and aerospace sectors owing to its higher hardness, creep strength, high thermal stability, and corrosion resistance in harsh environments.[1–8] Because of its high-temperature resistance property, Inconel 751 is extensively used in exhaust valves of heavy diesel engines. In general, exhaust valves are subjected to repetitive mechanical and thermal stresses, which causes valve failure in the sealing areas.[9] As a result, the exhaust valves must be thermally resistant and possessing higher fatigue life. In general, surface properties play an essential role on fatigue life of any component; therefore, better surface integrity of Inconel 751 is desired.[10] These applications mentioned enlighten the importance of achieving high surface quality during manufacturing of these parts. Grinding is the most commonly used secondary finishing operation and is one of the best processes to enhance the surface integrity of material. However, Inconel 751 is hard to grind due to its higher hardness, low thermal conductivity, intense strain hardening, and chemical affinity at high temperature.[11] Owing to low thermal conductivity of Inconel, extreme heat accumulates in the grinding zone potentially causing thermal damage to ground parts. From the abovementioned reasons, it can be incurred why a thorough research on the grinding of Inconel 751 is essential.
Knowledge transfer using Bayesian learning for predicting the process-property relationship of Inconel alloys obtained by laser powder bed fusion
Published in Virtual and Physical Prototyping, 2022
Cuiyuan Lu, Xiaodong Jia, Jay Lee, Jing Shi
Inconel refers to a family of austenitic nickel-chromium-based high-performance alloys which possess excellent properties of oxidation and corrosion resistance. While Inconel alloys exhibit excellent mechanical properties, their high hardness, high work hardening rate and low thermal conductivity (Choudhury and El-Baradie 1998) make them hard to machine. In this regard, LPBF offers an alternative to machining and mitigates the above challenges, and actually, the rapid cooling rate in LPBF can result in finer grains and improved mechanical properties (Wang, Shi, and Liu 2019; Wang et al. 2019). As such, Inconel alloys have become one of the popular alloy groups for LPBF, and among which Inconel 718 (IN718) is the most studied Inconel alloy for LPBF thanks to its excellent properties of high-temperature strength, fatigue and creep strengths, resistance to oxidation and corrosion and thus broad range of applications in aerospace and automobile sectors (Amato et al. 2012; Wang and Shi 2020).
Experimental studies on cryogenic CO2 face milling of Inconel 625 superalloy
Published in Materials and Manufacturing Processes, 2021
Aerospace and allied industries are in a quest to enter new and emerging markets, with a lookout for continuous improvements in their manufacturing processes. As a result, they are continually leveraging new and emerging technologies in the area of machine and machine tools to stay competitive and ahead of the competition. Even in the case of other market segments, there is a need for improvisation in the selection of materials and manufacturing processes to meet the challenges and conditions of the metal cutting industries of the future. A nickel-based superalloy, Inconel 625 is having higher concentrations of Cr, Mo, and Nb to stiffen the alloy’s matrix and thus exhibits high strength without the need for heat treatment. Besides, the alloy also possesses superior resistance to pit or indentation even in highly corrosive environments. Inconel 625 finds use in chemical plants, gas turbines, aerospace, marine industries, and nuclear power plants. Higher concentrations of Cr and Mo lead to retardation in machinability requiring higher cutting force. These attributes necessitate the need for heavy-duty machinery with special cutting tools and more rigid fixtures to overcome chatter and also to obtain desirable dimensional accuracy and surface finish.[1–3] The stringent and highly demanding quality standards, the rising cost of raw material and the need to minimize both internal and customer rejections while supplying the products to aerospace industries pose several challenges to the manufacturing process.